Page 1290-Unit 10 Fuel
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture
Living fuels, Variations in live fuels, Perennial and Annual Herbaceous Vegetation, Fuel Models with live
fuels, Crown Fires.
Define critical live fuel moisture and thresholds for various fuel types
Estimation based on time of year
Live fuel sampling (oven dry method)
- (Wet-dry)/dry
Online data sources (WFAS)
3 methods for obtaining life fuel moisture
Fuel Moisture Exchange with the atmosphere
Equilibrium Moisture Content
Environmental Factors Influencing Fuel Moisture
Define the relationship between RH, wind, and moisture content of fine and large fuels.
Shaded vs unshaded (fuel temp)
Aspect (lowest FM on West)
Elevation (high=low FM)
Slope (slope % affects solar heating)
Wind (whatever is happening to fuel.. wind makes it faster)
Environmental factors influencing Fuel moisture
Precip can raise fine dead fuel moisture more rapidly.
Takes longer in large dead fuels
precipitation duration affects fine vs large differently.
-large will hold onto moisture longer, fine fuels get to saturation point then dry out quickly.
Explain how the amount and duration of precipitation and soil moisture affect moisture content of fine
and large fuels
The fuel moisture time-lag concept and its value to firefighters
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
,Page 2290-Unit 10 Fuel
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
it varies by size class
1hr
-calculated from fine dead fuel charts
-rough estimate
-oven dry
10hr
-fuel moisture sticks
-NFDRS outputs
-oven dry
100 and 1000
-NFDRS outputs
-oven dry
-calibrated moisture meter
Describe how fuel moisture is determined for dead fuels in each of the four timelag catagories
the fuel moisture content at which a fire will not spread, or spreads only sporadically
-High Moisture of Extinction= higher moisture needed to extinct (chemical plants)
-low moisture of extinction= lower moisture needed to extinct (grasses)
Moisture of Extinction
Determine fuel moisture content for fine dead 1-hour timelag fuels from fuel moisture tables during
daylight conditions.
The amount of water in a fuel, expressed as a percent of the oven dry weight of that fuel. -(wet weight-
dry weight)/dry weight
Define fuel moisture content.
212 F
What is the oven temp for drying fuels?
found in living plants
range is 30-300%
varies over species, space, and seasons
Live fuel moisture
Found in dead plants
ranges from 2-30%
can change quickly
Dead fuel moisture
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
, Page 3290-Unit 10 Fuel
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Annuals-grows fast and dies, lower fuel moisture
Perennials-deep roots, higher fuel moisture
Evergreen- more leaves, more fuel moisture
Deciduous- loses leaves, lower fuel moisture
4 live fuels in the
Herbaceous and
Woody
categories
species/fuel model, Season, aspect, elevation, drought, diseases.
(not as affected my ambient air conditions as dead fuel)
Variations in live fuels
Month
Clouds and/or canopy cover shading
Time of day
Site location elevation difference
Aspect
Slope percent
Inputs used to determine fine dead fuel moisture
turgor means not limp.
Turgor
Water moving from higher concentrations to lower concentrations in a constant effort to establish
balance.
Diffusion
When there is no loss or gain of moisture between fuels and the surrounding air.
Equilibrium Moisture Content
amount of time it takes dead fuel to reach 63% of the difference between its initial moisture content
and its equilibrium moisture content
(1hr, 10hr, 100hr, 1000hr)
Timelag (dead fuel only)
1hr: 0-1/4 inch
10hr: 1/4 -1 inch
100hr: 1-3 inch
1000hr: 3-8 inch
Dead Fuel Timelag Categories
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture
Living fuels, Variations in live fuels, Perennial and Annual Herbaceous Vegetation, Fuel Models with live
fuels, Crown Fires.
Define critical live fuel moisture and thresholds for various fuel types
Estimation based on time of year
Live fuel sampling (oven dry method)
- (Wet-dry)/dry
Online data sources (WFAS)
3 methods for obtaining life fuel moisture
Fuel Moisture Exchange with the atmosphere
Equilibrium Moisture Content
Environmental Factors Influencing Fuel Moisture
Define the relationship between RH, wind, and moisture content of fine and large fuels.
Shaded vs unshaded (fuel temp)
Aspect (lowest FM on West)
Elevation (high=low FM)
Slope (slope % affects solar heating)
Wind (whatever is happening to fuel.. wind makes it faster)
Environmental factors influencing Fuel moisture
Precip can raise fine dead fuel moisture more rapidly.
Takes longer in large dead fuels
precipitation duration affects fine vs large differently.
-large will hold onto moisture longer, fine fuels get to saturation point then dry out quickly.
Explain how the amount and duration of precipitation and soil moisture affect moisture content of fine
and large fuels
The fuel moisture time-lag concept and its value to firefighters
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
,Page 2290-Unit 10 Fuel
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
it varies by size class
1hr
-calculated from fine dead fuel charts
-rough estimate
-oven dry
10hr
-fuel moisture sticks
-NFDRS outputs
-oven dry
100 and 1000
-NFDRS outputs
-oven dry
-calibrated moisture meter
Describe how fuel moisture is determined for dead fuels in each of the four timelag catagories
the fuel moisture content at which a fire will not spread, or spreads only sporadically
-High Moisture of Extinction= higher moisture needed to extinct (chemical plants)
-low moisture of extinction= lower moisture needed to extinct (grasses)
Moisture of Extinction
Determine fuel moisture content for fine dead 1-hour timelag fuels from fuel moisture tables during
daylight conditions.
The amount of water in a fuel, expressed as a percent of the oven dry weight of that fuel. -(wet weight-
dry weight)/dry weight
Define fuel moisture content.
212 F
What is the oven temp for drying fuels?
found in living plants
range is 30-300%
varies over species, space, and seasons
Live fuel moisture
Found in dead plants
ranges from 2-30%
can change quickly
Dead fuel moisture
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
, Page 3290-Unit 10 Fuel
290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Annuals-grows fast and dies, lower fuel moisture
Perennials-deep roots, higher fuel moisture
Evergreen- more leaves, more fuel moisture
Deciduous- loses leaves, lower fuel moisture
4 live fuels in the
Herbaceous and
Woody
categories
species/fuel model, Season, aspect, elevation, drought, diseases.
(not as affected my ambient air conditions as dead fuel)
Variations in live fuels
Month
Clouds and/or canopy cover shading
Time of day
Site location elevation difference
Aspect
Slope percent
Inputs used to determine fine dead fuel moisture
turgor means not limp.
Turgor
Water moving from higher concentrations to lower concentrations in a constant effort to establish
balance.
Diffusion
When there is no loss or gain of moisture between fuels and the surrounding air.
Equilibrium Moisture Content
amount of time it takes dead fuel to reach 63% of the difference between its initial moisture content
and its equilibrium moisture content
(1hr, 10hr, 100hr, 1000hr)
Timelag (dead fuel only)
1hr: 0-1/4 inch
10hr: 1/4 -1 inch
100hr: 1-3 inch
1000hr: 3-8 inch
Dead Fuel Timelag Categories
290-Unit 10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
290-Unit
290-Unit
10 Fuel
10 Fuel
Moisture290-Unit
Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
10 Fuel Moisture2026/2027!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
