01-3- S190- EP Convection Radiation Conduction.

Genesee Fire Rescue

CommunityWildfireMeeting

Denver Fire at Black Forest Fire

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EP

Convection

Radiation

Conduction

Heat Transfer

Three environmental factors of wildfire behavior that affect the

spread of wildland fire.

TemperatureWind

Increases supply of oxygen.Drives convective heat into adjacent fuels.Influences direction of spread and spotting.Carries away moist air replacing it with drier air.Dries fuels.Raises fuel moisture if the air contains moisture.

Relative HumidityAs RH increases, fuel moisture increases.

PrecipitationIncreases fuel moisture

Weather

Strong Wind.Sudden changes in wind direction and velocity due to

weather fronts.High, fast-moving clouds may indicate unusual surface

winds.Unexpected calm may indicate wind shift.Thunderstorms above or close to the fire.Unusually high temperatures and low relative humidity.Dust devils and whirlwinds developing.Bent smoke column.

Indicators of Problem and Extreme Fire Behavior

Weather Indicators

Aspect

SOUTH

NORTH

Heavy fuelsShadeMoist

Topography

Light fuelsSunnyDry

Steep Slopes Cause Rapid Fire Spread

Flame is closer to

and preheating

fuel

Convection and Radiant Heat

Box Canyon & Chimney Effect

Radiant HeatAcross Narrow Canyon

Spotting Across Narrow Canyon

Mountains CauseChanneling of Wind


Steep slopes.Chutes, saddles, and box canyons which

provide conditions for “chimney effect.”Narrow canyons may increase fire spread

by radiant heat and spotting.

Topography Indicators

Fuel Characteristics

Fuel Moisture Size and Shape Fuel Loading Horizontal Continuity Vertical Arrangement

Fuels

Fuel MoistureThe amount of water in a fuel

expressed as a percentage of the oven-dry weight of that fuel.

CATEGORIES

• 1-hour fuels: 0 – ¼ inch in diameter• 10-hour fuels: ¼ – 1 inch in diameter• 100-hour fuels: 1 – 3 inches in

diameter• 1000-hour fuels: 3 – 8 inches in

diameter

Categories of FuelLight Fuels: Leaves Grass Shrubs

Heavy Fuels: Limbs Logs Stumps

Fuel Loading

The quantity of fuels in an area

Horizontal Continuity &Vertical Arrangement

Horizontal Continuity: Uniform Patchy

Vertical Arrangement: Ground Surface Aerial

Uniform Fuels

Patchy Fuels

Vertical Arrangement of Fuels

Aerial Fuels

Ladder Fuels

Surface Fuels

Ground Fuels

Unusually dry fuels.Large amount of light fuel (shrubs, grass,

needles).Fuels exposed to direct sunlight.Fuels dried by prolonged drought.Ladder fuels that allow a surface fire to move

into the crowns of shrubs or trees.Crown foliage dried by surface fire.Concentration of snags.


Fuel Indicators

Fire Behavior Terms

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CreepingFire burning with a low flame and

spreading slowly.

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RunningFire spread rapidly with a well defined head.

*Click on image to play video

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SpottingFire producing sparks or embers that are carried by

the wind or convection that start new fires


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Torching

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Flare upSudden acceleration of fire spread or intensity, but of

relatively short duration.

Fire WhirlA spinning, moving column of ascending air rising within

a vortex and carrying aloft smoke, debris, and flames.

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CrowningFire advances from top-to-top of trees or shrubs more or less independently of the surface fire.


Keep an eye on the smoke column. Indicates direction of fire spread, location of spot fires, and changes in fire intensity.

Many simultaneous fires starting or smoldering fires beginning to pick up in intensity.

Fire begins to torch small groups of trees or shrubs.Frequent spot fires occurring.Fire-whirls beginning to develop inside the main fire.Crown fires.


Fire Behavior Indicators

Tactical Modes

Offensive

Defensive

Combination

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Attack and contain the fire

Offensive Mode

Defensive Mode

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Set up at the houseClear flammable materialProtect house from flame and sparks

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If too much fire or no defensible space, LEAVE!Return after fire front passes

Defensive Mode

Structure engines at home for protection

Attack fire and and drive flames away from house

CombinationOffensive and Defensive Mode

# 1

# 2 # 3

# 4

Structure Triage “Size-Up”

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1. Well-irrigated area encircling structure for at least 30 feet on all sides. Plantings limited to carefully spaced low flammability species.

2. Provide added protection with “Fuel Breaks” like driveways, gravel walkways and lawns.

5 Top Effective Mitigation MeasuresCase Study of Witch and Guejito Fires

3. Keep vegetation pruned and limb trees 6–10 feet from ground. Remove leaf /needle clutter and dead and overhanging branches.

4. Periodically inspect your property, clearing dead wood and dense vegetation at a distance of at least 30 feet from your house.

5. Is the structure free of an attached wood fence?

Footnote: Of the 241 homes impacted, 13 had wood shake roofs and all 13 were destroyed. A total of 89 were destroyed or damaged.

Waldo Canyon Fire - 2012

Fire Brand Experiment

Shut off natural gas and propane. Place metal (not wooden) ladders against the lee side

of your house. Connect and turn off outside water hoses and nozzles. If time permits, remove combustibles (patio furniture,

firewood, etc.) within 30 feet of your home. Close windows and doors to the house to prevent

sparks and embers from blowing inside. Cover gable vents if time permits.

Close all doors inside the house to prevent draft. Turn OFF fans, air conditioner, furnace.

Things YOU can do to help us

Move furniture from windows. Take down your drapes and curtains and close all

blinds to deflect heat. Fill all bathtubs, sinks and other containers with

water to deflect heat. Leave exterior lights on so responders can find your

home at night. Put on natural fiber clothing and take your 72-Hour

kit with you. Leave front door unlocked. Put a white flag (towel, pillow case, etc.) outside

where it can be seen from the roadway.

Only Do The Above IF YOU HAVE TIMEEvacuate Now Means NOW

Black Forest Fire 2013 – Video courtesy of Colorado Springs Fire Department

Questions?

Genesee Fire Rescue

01-3- S190- EP Convection Radiation Conduction.

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