Student Guide to the Illustrations and Exercises

1
Student Guide to the Illustrations and
Exercises The presentation and completed
worksheets as were shown in the Unit 12 FLAME
Introduction PowerPoint materials are duplicated
here. The illustrations show the completed
worksheets and can serve as a guide and
reference. The exercises do not show
completed information the student is to complete
the worksheet in doing the exercise.
Worksheets are in black white, and they lack
the colored sections that mark the 3 application
stages on the worksheet in the PPt presentation.
Diagrams illustrate the fire behavior situation,
rather than the animations that are shown in the
PPt program.
2
Illustration 1 A change in fuel type
Next big change fuel type changes from grass to
litter
x
x
Observed conditions Fire moves upslope in
grass with no wind. Conditions do not favor
crown fire Fire will move in grass to midslope
in 20 minutes
Weather Forecast No changes
1X
14X
x
½ slope in 20 min
½ slope in 4 hrs
If the fire moves 14X slower it will take 14X
longer to go the same distance. 14X(20 min) 4
hrs.
3
Exercise 1 Litter to brush crown fuel
Next big change
Observed conditions Fire moves upslope in
woodland litter with no wind RH 20. Fire will
move in litter to midslope in 2 hours
Weather Forecast No changes
4
Illustration 2 Wind change, surfacing mountain
wave
Note these are full force surfacing winds ,
involving a mountain range, not lee-side winds
sheltered by a hill.
Next big change wind aloft surfaces on the fire
-
30
25
5
x
x
10 poles
5
20
5
15
Observed conditions Grass fire on flats below
major mountain range moving 1 utility
pole-span every 8 minutes Wind west 5 RH
30 Crew building line 10 pole-spans east of the
fire escape time needed 5 min.
5
15
3X
Note These are full force surfacing ridgetop
winds, not lee-side winds sheltered by a hill.
1 pole in 8 min
1 pole in 2 min
Before the wind increase, a single pole-span
would provide sufficient distance from the fire
to allow escape, but after the wind increase it
would take a 3-pole span to provide the
needed 5-minute escape window. Best to plan for
the larger escape window.
5
Exercise 2 Wind change This photo shows the
actual situation considered in this exercise.
Next big change
NW 3
Observed conditions 9am July morning Upslope
winds developing Wind 3 mi/hr from NW
Temp 82 RH 36 Smoke from fire on ridge is
capped by inversion and shows a south wind
above Fire on north side is backing in grass
into the light NW surface winds Observed spread
time is 1 chain in 30 min.
6
Illustration 3 Wind and slope change
Next big change fire moves upslope into more
wind
15
15
slope 50
x
x
4
8
4
Observed conditions Late morning fire in small,
continuous brush late morning Wind on the fire
4 mph RH 15 Fire will reach the base of the
slope in 1 hour Wind speed on the slope
reported at 8 mph eye-level (OK for small
brush)
Weather Forecast No significant changes
through early afternoon
4
8
0
4
2½ X
3X
x
to slope in 1 hr
Up slope in 20m
7
Next big change

Exercise 3 Wind and slope change
Observed conditions Early afternoon fire
backing down a east-facing 50 slope in litter
RH 40 Expected to cover the lower half of the
slope to the drainage in 4 hrs Little wind on
the east aspect sheltered by terrain and
vegetation west-aspect slope is 40-50 Early
season live fuel moisture is high, and makes
crown fire unlikely
8
Next big change litter to crown EWS increase
40-50 slope
40
20
?
x
x
Illustration 4 Wind and fuel change, slope
reversal
15
Observed conditions Early morning in september,
fire is backing down a north slope in deep
litter Temp is 65oF RH is 40 Fires progress
will put it at the bottom by about noon (6
hours) South slope is chaparral, crown fire
occurred in brush yesterday
8
back
20X
140X
x
lwr slope in 6 hrs
lwr slope in 3 min
In real life the change will take place over
time, but once a crown run gets established
it can move that distance in a few minutes.
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Next big change
Slope 60-65
Exercise 4 Wind and fuel change, litter on
lower slope to crown fire on upper slope
10
Current
Expected
Exercise 5 Flanking litter fire onto grass slope
Next big change
Relative Humidity
Litter (sfc)
Litter (sfc)
Fuel
Crown (aer)
Crown (aer)
Grass (sfc)
Grass (sfc)
20-ft pred or EL obs WS
Eye-lvl WS obs
Effect. Wind Speed On Fire
Eye-lvl WS fire
20-ft or EL obs WS fire
Observed conditions Temp 85oF RH 26 Time is
early afternoon Fire burning actively in
litter Slope nearly flat Essentially calm in
trees Smoke drifts straight up in trees, then
drifts East Spread 1/8 of slope in 2 hrs
Adjacent west slope is grass, about 30 slope
Midflm WS fire
Midflm WS fire
Slope cont fire
Slope cont fire
Curr EWS fire
Expct EWS fire
EWS Ratio big/small
ROS Ratio
Faster
Slower
Obs. spread
Obs Sprd/RosR
Obs SprdXRosR
Predicted spread
11
So. Canyon Fire
backing litter fire
7 min
60 hrs
Actual 9 min
Next big change CFP litter to crown wind
increase
Ridge
20
10
x
60 hrs
x
Stream
Observed conditions July drought backing fire
in litter Light upslope wind 20 RH Fire may
reach bottom this shift after 60 hour spread
from top to bottom
Weather Forecast Dry cold front predicted WSW
winds to 30 mph RH 10
30
30
back
60X
x
500X
Slope in 7 min
Slope in 60 hrs
Crown fire indicators - Seasonal drought plus
overall drought - RH below 20 - Backing fire
causes torchouts - Crown fire /or torching on
this or nearby fires
12
Exercise
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