Geoscience Reference
In-Depth Information
Fire
weather
observations
Temperature,
relative humidity,
wind speed,
rain
Wind
speed
Temperature,
relative humidity,
rain
Temperature,
rain
Fuel
moisture
codes
Fine Fuel
Moisture
Code (FFMC)
Duff Moisture
Code
(DMC)
Drought
Code
(DC)
Initial Spread
Index
(ISI)
Buildup
Index
(BUI)
Fire
behavior
indices
Fire
Weather
Index (FWI)
Fig. 7.3
Structure of the Canadian Forest Fire Weather Index (FWI) System. See Box 7.3 for
system description
Box 7.2 Time Scales and Early Warning
Long-term early warning products (or seasonal forecasts) provide an indication
of anticipated global trends in fi re danger over the course of the upcoming fi re
season. Short-term early warning products (1-2 weeks) provide information
for large-scale tactical decision-making that requires “spool-up” time to
implement fi re management action plans such as arranging the transfer of
helicopters, fi xed-wing air tankers, or fi re fi ghters and equipment across inter-
national borders. Early warning of 1-7 days provides information for strategic
decision-making, such as prepositioning suppression resources in the most
critical areas to most effectively control new fi res and contain ongoing fi res.
The Canadian Forest Fire Weather Index (FWI) System (Van Wagner
1987
) was
used for the Global EWS-Fire since it is the most widely used system, internation-
ally (Table
7.2
). As a brief summary, there are six components in the FWI System
that refl ect fuel moisture and general fi re behavior at a landscape scale, as infl u-
enced by weather (see Fig.
7.3
). There are three fuel moisture codes representing the
moisture content of litter and other dead fi ne fuels (Fine Fuel Moisture Code,
FFMC), surface organic matter of moderate density, such as the F layer of forest
soils (Duff Moisture Code, DMC), and deep, compact soil organic layers, such as
the H layer of forest soils (Drought Code, DC). The fuel moisture codes are also
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