Fire Behavior Case Studies

Rough Draw Wildfire

  1. Introduction
  2. Fuels
  3. Topography
  4. Weather
  5. Fire Behavior
  6. Causal Factors

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Introduction

This case study examines a fire that occurred during mid-August, 2003 in the Absaroka Mountains southeast of Livingston, Montana.

Review the Fuels, Topography, and Weather sections (below) to learn about the environmental conditions for this fire.

Then, continue to the Fire Behavior section to make a prediction about the types of fire behavior you would expect for the given conditions. Once you have made this prediction, go to the Causal Factors section to answer a summary question about the causal factors for this fire.

Map of south-central Montana, eastern Idaho, and northwestern Wyoming.
Map depicting fire and related data source locations in south-central Montana.

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Fuels

Fuels in the area of interest included lodgepole pine, sub-alpine fir, spruce fir mix, douglas fir, limber pine and white bark pine.

The canopies in this part of the forest were fairly continuous within a densly packed forest. At the surface, semi-cured herbaceous and woody fuels were intermixed with dead and down material such as jackpots containing heavier fuel. It is typical for dead fuel moistures to be low in August, but dryness was enhanced by pre-existing drought conditions. Live fuel moisture levels within the tree species were also below normal.

Examine the photos and data products below (you can click them to see enlarged versions) to form an understanding of the fuel situation for this fire. For more information about the data products presented, refer to the Assessing Fire Danger module in the Advanced Fire Weather Forecasters Course.

Wooded area with lush vegetation.
Shaded slopes like this one were covered by numerous herbaceous and woody surface fuels, which were semi-cured, although they appeared to be green.
Standing and down trees.
Fuel moisture was low in both the canopies of live trees and in dead and down fuels.
Aerial photo of canyon flanks covered with dense forest.
Forest canopies were dense and continuous in many areas.
U.S. Drought Monitor, 12 Aug 03.
Large portions of the western US were suffering extreme to exceptional drought conditions.
Observed 100-hr fuel moisture, 16 Aug 03.
Hundred-hour fuel moistures levels were below 10%.
Observed 1000-hr fuel moisture, 16 Aug 03.
Thousand-hour fuel moistures levels ranged between 6-15%.

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Topography

The Ojo Feliz fire occurred in a region situated to the lee of the north-south oriented Sangre de Cristo mountain range, with peaks over 13,000 ft tall. The fire area ranged in elevation between 7350-8300 ft.

The terrain may be characterized as a gently sloped plateau with one embedded steep canyon. The general slope was calculated at 25-30% for this fire.

Examine the photos below (you can click them to see enlarged versions) to form an understanding of the terrain configuration for this fire.

Overhead view of the Mission Creek drainage, looking from the south.
Mission Creek drainange and Rough Draw , 16-Aug-2003.
Overhead view of the mouth of Mission Creek canyon, looking toward the south.
The mouth of Mission Creek Canyon, 16-Aug-2003.
Rockly upper slopes above Rough Draw.
Steep rocky slopes and chimney formations were observed.
A view down Rough Draw and the Mission Creek drainage.
Dense conifer stands were found in the valleys.
Soil moisture percentiles.
Soil moisture percentiles ranged between 10 and 30 as compared to 1960-2003 averages.

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Weather

As this event unfolded, a large disturbance spread across the northern Rockies from the northwest. High-based thunderstorms were spawned ahead of the cold frontal boundary as it pushed eastward. Thunderstorm outflows generated strong gusts and shifting winds. With frontal passage thunderstorms became wetter and later brought rain to the fire area.

In the area of interest, relative humidity values were in the 20s during the initial outflow event with recoveries into the 30s. Skies were partly cloudy.

Examine the data products below (you can click them to see enlarged versions) to form an understanding of the weather context for this fire. Data source locations are indicated on the basemap.

ETA MSLP, 00utc, 7 Aug 03.
A weak surface cold front moved through the area during the afternoon.
ETA 500 and 700 hPa temperatures, 00utc, 17 Aug 03.
A strong mid-level thermal ridge increased instability over the fire area.
ETA 700 hPa winds, 00utc, 7 Aug 03.
A moderate mid-level cold front approached the fire area during the afternoon.
Satellite IR, 0330utc, 17 Aug 03.
Wet showers and thunderstorms moved across the fire area during the late afternoon and evening hours. This activity was in association with the mid level front.
ETA 500 hPa hts and winds, 00utc, 17 Aug 03.
A shortwave in association with the cold front provided the catalyst for shower and thunderstorm development over and around the fire area during the late afternoon and evening hours. Drier cells with a small coverage area propagated out ahead of a wetter band of storms, which approached the fire area during the late afternoon.
METARs, 21utc, 16 Aug 03.
METARs from 21utc 16 Aug 03. (Click to open the data loop in a new window.)

Text Products

RAWS Data

Station            GOES ID  Elev   Lat       Long
===========================================================
MT WICKED CREEK    323F2314 7604   45:16:14  110:32:36 
                                  Dew                   Fuel   Peak  Bat  Fuel
                   Day/Time   Tmp Pt  Wind   Pcpn Rh    Temp   Wind  Volt Moist
====================================================================================
MT WICKED CREEK     17/1401Z   48/ 34/3006/  1.60 RH 59 FT 32/ 32G10 13.1 FM  0 SR 120
MT WICKED CREEK     17/1301Z   48/ 35/3401/  1.60 RH 61 FT 32/ 34G03 12.8 FM  0 SR  84
MT WICKED CREEK     17/0201Z   68/ 46/1808/  1.56 RH 46 FT 32/ 24G26 13.2 FM  0 SR  48
MT WICKED CREEK     17/0101Z   73/ 43/1807/  1.53 RH 34 FT 32/ 14G18 14.1 FM  0 SR 455
MT WICKED CREEK     17/0001Z   74/ 41/1909/  1.53 RH 31 FT 32/ 17G20 14.2 FM  0 SR 407
MT WICKED CREEK     16/2301Z   74/ 42/1711/  1.53 RH 32 FT 32/ 20G24 14.2 FM  0 SR1114
MT WICKED CREEK     16/2201Z   75/ 42/2011/  1.53 RH 31 FT 32/ 21G22 14.2 FM  0 SR 611
MT WICKED CREEK     16/2101Z   80/ 44/2609/  1.53 RH 29 FT 32/ 25G23 14.1 FM  0 SR  MM
MT WICKED CREEK     16/2001Z   79/ 43/2804/  1.53 RH 28 FT 32/ 24G19 14.2 FM  0 SR  MM
MT WICKED CREEK     16/1901Z   74/ 44/1509/  1.53 RH 35 FT 32/ 14G17 14.3 FM  0 SR  MM
MT WICKED CREEK     16/1801Z   75/ 43/1508/  1.53 RH 33 FT 32/ 16G16 14.2 FM  0 SR  MM
MT WICKED CREEK     16/1701Z   75/ 45/1609/  1.53 RH 35 FT 32/ 14G16 13.9 FM  0 SR  MM
MT WICKED CREEK     16/1601Z   71/ 40/1710/  1.53 RH 33 FT 32/ 18G15 14.0 FM  0 SR1438
MT WICKED CREEK     16/1501Z   69/ 37/1613/  1.53 RH 31 FT 32/ 16G17 14.5 FM  0 SR1029
MT WICKED CREEK     16/1401Z   68/ 34/1708/  1.53 RH 29 FT 32/ 16G12 13.3 FM  0 SR 491
MT WICKED CREEK     16/1301Z   63/ 33/2604/  1.53 RH 33 FT 32/ 15G06 12.8 FM  0 SR  96
MT WICKED CREEK     16/1601Z   71/ 40/1710/  1.53 RH 33 FT 32/ 18G15 14.0 FM  0 SR1438
MT WICKED CREEK     16/1501Z   69/ 37/1613/  1.53 RH 31 FT 32/ 16G17 14.5 FM  0 SR1029
MT WICKED CREEK     16/1401Z   68/ 34/1708/  1.53 RH 29 FT 32/ 16G12 13.3 FM  0 SR 491
MT WICKED CREEK     16/1301Z   63/ 33/2604/  1.53 RH 33 FT 32/ 15G06 12.8 FM  0 SR  96
MT WICKED CREEK     16/0201Z   77/ 41/1011/  1.30 RH 28 FT 32/ 07G22 13.1 FM  0 SR  24
MT WICKED CREEK     16/0101Z   79/ 40/0914/  1.30 RH 25 FT 32/ 08G20 14.3 FM  0 SR 168
MT WICKED CREEK     16/0001Z   80/ 42/0712/  1.30 RH 26 FT 32/ 07G22 14.4 FM  0 SR 144
MT WICKED CREEK     15/2301Z   84/ 43/3310/  1.30 RH 24 FT 32/ 32G17 14.0 FM  0 SR 563
MT WICKED CREEK     15/2201Z   83/ 45/3113/  1.30 RH 27 FT 32/ 31G19 14.0 FM  0 SR1066
MT WICKED CREEK     15/2101Z   77/ 44/3212/  1.30 RH 32 FT 32/ 32G19 14.1 FM  0 SR 311
MT WICKED CREEK     15/2001Z   78/ 45/3111/  1.30 RH 32 FT 32/ 32G19 14.2 FM  0 SR 611
MT WICKED CREEK     15/1901Z   75/ 42/3113/  1.30 RH 31 FT 32/ 31G19 14.5 FM  0 SR 503
MT WICKED CREEK     15/1801Z   75/ 43/3113/  1.30 RH 33 FT 32/ 31G17 14.6 FM  0 SR  MM
MT WICKED CREEK     15/1701Z   77/ 44/2903/  1.30 RH 31 FT 32/ 31G05 13.9 FM  0 SR  MM
MT WICKED CREEK     15/1601Z   75/ 44/3302/  1.30 RH 34 FT 32/ 13G04 13.9 FM  0 SR1438
MT WICKED CREEK     15/1501Z   72/ 41/1304/  1.30 RH 33 FT 32/ 12G06 14.6 FM  0 SR 491
MT WICKED CREEK     15/1401Z   70/ 43/1102/  1.30 RH 38 FT 32/ 12G05 13.2 FM  0 SR 359
MT WICKED CREEK     15/1301Z   67/ 41/1704/  1.30 RH 39 FT 32/ 17G06 12.8 FM  0 SR  7

NOAA/BLM

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Fire Behavior

Question

What kind of fire behavior do you think resulted from the combination of fuels, topography, and weather conditions you have seen for this event?

  1. Smoldering, creeping surface fire
  2. Active surface fire with isolated torching and short-range spotting
  3. Extreme fire behavior with an independent crown run and erratic spotting

Feedback

The correct answer is 3. This fire produced an intense short-duration crown run that was independent of the surface fire. Down-canyon outflow winds helped a fairly low-intensity surface fire transition to the forest canopy, where it blew up into a crown run that was estimated to spread 100-150 acres in 8-10 minutes. Once the fire was established in the canopy, it pushed strongly up-canyon. This push was enhanced by the surrounding terrain (chimney effect) and localized strong winds generated by the fire. Several spot fires resulted during this crown run.

At the same time, another outflow was generated by a more moist rain cell located up-canyon from the crown fire. The plume generated by the crown fire was undercut by this outflow and ended up providing additional spotting across the Mission Creek drainage. Steady rain quickly set in after the plume collapse and subsequently ended this short-duration fire event.

Review the following photos and video clips to see what happened.

Test fire burns in surface vegetation.
16 August, mid-afternoon: Crews prepared a line for a burnout in the upper reaches of Mission Creek during the early to middle afternoon hours. They lit test burns waiting for RH values to decrease enough for the semi-cured surface fuels to carry the fire.

Isolated torching and some surface fire was observed between 15:30 (2130 UTC) and 16:15 (2215 UTC). RH values were measured in the 20s at this time.
Crew scrambles up the scree slope.
Winds trigger a retreat (16:00-16:35 local time; 2200-2235 UTC).

Outflow gusts became more frequent and stronger as the cold front approached the area from the west. Around 16:35, fire activity picked up significantly when a strong outflow blew down-canyon along Mission Creek. The safety officer reported two strong gusts, around 30 mph. Torching was observed in several trees and the division supervisor told the crews to head for the safety zone, a nearby scree slope.
Crown run.
The fire began propagating through the forest canopy and expanded rapidly. Extreme behavior was observed as the crown run swiftly moved up-canyon. While crews watched, the fire raced through a continuous stand of sub-alpine fir along the lower edge of the scree slope where they sought shelter.
Crew member observes the intense fire below.
Crew members watched as the stand they had just been working in is consumed by the intense crown run.
Crown run.
Crew members were happy to have escaped the dangerous blow-up.
A view of the aftermath.
Charred remains of trees and an abandonded fire hose were all that remained.

Videos

The following videos illustrate the types of fire behavior observed. The first video clip, recorded by a member of the Bridger fire crew on the afternoon of August 16th, 2003, shows some dramatic footage of the crown fire in the trees below the scree slope.

Still frame from the video clip.
(Click to play this video clip.)

The second video clip, recorded 2 minutes after the preceding one, shows the results of the crown fire. The forested area below the crew has been completely transformed.

Still frame from the video clip.
(Click to play this video clip.)

The last video clip, recorded 10 minutes after the previous sequences, shows the crew members taking shelter under tarps as winds have shifted and rains arrived. Rain became steady between 17:10-17:20, causing fire activity to rapidly decrease. Fifteen to twenty hundredths of an inch of rain fell later that day.

Still frame from the video clip.
(Click to play this video clip.)

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Causal Factors

Question

Why did this part of the Rough Draw fire develop into an intense crown fire? Select the main factors that allowed this to happen. (Choose all that apply from the list below.)

  1. Extremely dry surface fuels
  2. Abundand ladder fuels
  3. Dry dead & down jackpots
  4. Continuous and dry canopy
  5. Densely packed forest
  6. Trees had fairly high live fuel moisture levels
  7. Steep terrain with chimney formations
  8. Low soil moisture levels
  9. South-facing aspect
  10. Strong, gusty outflow winds
  11. Temperatures well above normal
  12. Very low humidity

Feedback

The correct answers are 2, 3, 4, 5, 7, and 10. Fuels, topography, and weather factors all came into play. The crown fire broke out within a forested area that was densely packed with a continuous and dry canopy. Topography was steeply sloped and upper reaches of the drainages above the fire acted as chimneys when up-canyon winds were co-aligned. Finally, the fire was intensified by strong, gusty outflow winds from showers ahead of the approaching front.

Other factors facilitated the transition of the surface fire into the canopy. These included fuel jackpots, low live fuel moistures in the tree canopies, and efficient laddering within the sub-alpine fir. (This conifer is notorious for efficient torching during drought years because its limbs reach fairly close to the ground.)

Although soil and duff layers were dry, many of the surface fuels were only partially cured. Afternoon RH levels were also not considered to be particularly low. These mitigating factors reduced surface fire intensity both prior to and during the crown fire event. As a result, the fire propagated as an independent crown fire.

You have now completed this case study.

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