1. Wildland Fire Behavior

2. Component 1 Fuel-grass, shrub, timber litter, logging slash
01-02-S390-VG

3. Less than 30, treat as a dead fuel.
LIVE FUEL MOISTURE
STAGE OF VEGETATIVE DEVELOPMENT
________________________________________
Fresh foliage, annuals developing early in growing cycle.
Maturing foliage, still developing with full turgor.
Mature foliage, new growth complete and comparable to older perennial foliage.
Entering dormancy, coloration starting, some leaves may have dropped from stem.
Completely cured.
MOISTURE
CONTENT
Percent
300
200
100 50
Less than 30, treat as a dead fuel.
01-10-S390-VG

4. PROBABILITY OF IGNITION
A rating of the probability that a
glowing firebrand will cause a fire.
01-11-S390-VG

5. Wind
20 mi/h
20 mi/h
10 mi/h
3 mi/h
01-13-S390-VG

6. Fuel exposure to wind Unsheltered (ridgetops) Wind Partly sheltered
(under timber
midslope, wind
on slope)
Partly sheltered
(patchy timber)
Fully sheltered
(under timber,
flat or gentle
slope, near base
of steep mtn.)
Unsheltered (no foliage,
near clearings)
01-14-S390-VG

7. PERCENT SLOPE X 100 % RISE IN FEET % SLOPE = RUN IN FEET RISE RUN
01-16-S390-VG

8. A MATHEMATICAL MODEL IS A SET OF EQUATIONS
02-04-S390-VG

9. ASSUMPTIONS OF THE FIRE SPREAD MODEL
1. Fire is spreading at the flame front.
2. Fire is free burning.
3. Fine fuels control rate of spread.
4. Uniform and continuous fuels.
5. Surface fire.
6. Uniform weather and topography.
02-05-S390-VG

10. RATE OF SPREAD DISTANCE/TIME
ENDING
TIME
STARTING
TIME
DISTANCE
RATE OF SPREAD DISTANCE/TIME
02-09-S390-VG

11. FLAME LENGTH FEET
02-12-S390-VG

12. POINT SOURCE Point source model is designated for fires
burning on flat ground or where the wind
is blowing in the direction of the slope plus
or minus 30°.
upslope
max
slope
± 30º
02-15-S390-VG

13. SPREAD CALCULATION SD=PT X ROS SD = SPREAD DISTANCE PT= PROJECTION TIME ROS = RATE OF SPREAD
02-16-S390-VG

14. SPREAD DIRECTION NO WIND WIND WIND WIND UP SLOPE UP SLOPE UP SLOPE
DOWN
SLOPE
DOWN
SLOPE
DOWN
SLOPE
02-18-S390-VG

15. POINT SOURCE PREDICTION LIMITATIONS
Calculations with windspeeds less than
2.5 miles per hour are generally too low.
Better predictions result with
windspeeds greater than 2.5 miles
per hour.
02-21-S390-VG

16. FIRE PERIMETER AND SHAPES
Fire perimeter and shapes are based on
smooth ellipses - actual perimeter of
the fire edge would likely be greater
length and follow topographic relief.
02-23-S390-VG

17. APPROXIMATE FIRE SHAPES ASSOCIATED WITH MIDFLAME WINDSPEEDS OF…..
Wind Direction
Fire Start
7.5 mi/h
2.5 mi/h
10 mi/h
15 mi/h
5 mi/h
02-24-S390-VG

18. AREAS OF USE SUPPRESSION
Determination of locations to place crews,
equipment, helicopters and fuel breaks.
Development of the wildland fire
situation analysis.
02-25-S390-VG

19. PRESCRIBED BURNING Distance between spot fires to accomplish
an objective.
Calculating timing of ignition to take
advantage of diurnal weather patterns.
Managing wilderness fires.
Development of escaped fire contingency
planning.
02-27-S390-VG

20. EFFECTIVE WINDSPEED The midflame adjusted for the effect
of slope on uphill fire spread.
02-37-S390-VG

21. EXAMPLES OF EFFECTIVE WINDSPEED
3 mi/h
EFFECTIVE
WINDSPEED
IS 5 mi/h
60%
5 mi/h
02-38-S390-VG

22. MAXIMUM SPOTTING DISTANCE
When torching trees, piles or wind-
driven surface fires loft firebrands,
which are then carried by the
prevailing wind.
02-43-S390-VG

23. SOURCES OF FIREBRAND Torching trees Burning pile
Spreading surface fire
02-44-S390-VG

24. FACTORS RELATING TO THE SPOTTING PROBLEM
Probability of production of
firebrands.
Windspeed.
Fire intensity.
Number of firebrands
02-45-S390-VG

25. Dispatching Priorities
FUELS
WEATHER
TOPOGRAPHY
03-05-S390-VG

26. Predicting “Real Time” Fire Behavior Running Surface Fire Wildland Fire Situation Analysis(WFSA)
03-06-S390-VG

27. Prescribed Burning Estimate the behavior of escapes or spots.
Assess fuel and weather conditions at burn time.
Develop burn prescriptions.
Develop containment and control plans.
03-07-S390-VG

28. FIRE PLANNING Preattack Describing consequences
Environmental documents
03-09-S390-VG

29. Spread Distance Elapsed Time Rate of Spread =
03-28-S390-VG

30. FLAME LENGTH* Indicator of intensity Observable
*Remember flame length is not equal
to flame height.
03-30-S390-VG