Fire Index - Richards Bay
FWI Help Guide - Operational Interpretation |
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L = low fire danger
M = moderate fire danger
H = high fire danger
VH = very high fire danger
E = extreme fire danger
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Codes/Indices
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Values
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Triggers
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Fine Fuel Moisture Code
Time Lag = 16 Hours
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0~ 101
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Í 58 Þ
= 74 Þ
³ 86 Þ
³ 92 Þ
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No fire ignitions
50% fire ignitions
All fires will readily ignite
Extreme fire behaviour
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Duff Moisture Code
Time Lag = 12 DAYS
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0 ~150
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> 30 Þ
> 40 Þ
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H
VH SUSPEND the issue of fire permits
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Drought Code
Time Lag = 52 DAYS
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0 ~ 800
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³ 200 Þ
³ 300 Þ
³ 350 Þ
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H
VH SUSPEND the issue of fire permits
Prolonged Mop Up following fires
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Initial Spread Index
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0 ~100
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> 10 Þ
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Rapid Spread of fires
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BuildUp Index
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0 ~200
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> 40 Þ
> 60 Þ
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H
VH SUSPEND the issue of fire permits
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Fire Weather Index
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0 ~150
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³ 30 Þ
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Extreme Fire
Intensity / Control Difficulty
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The moisture codes (FFMC, DMC and DC) indicate what fuels will be involved and their ease of ignition. This will vary during the season. Each code must be considered to assess potential burning characteristics.
Example: 1
FFMC = 86 DMC = 25 DC = 120
These ratings indicate:
- fine fuels will ignite easily
- fire will involve the light fuels and to a limited extent the medium and duff layer fuels
- fire will not become deep seated
Example: 2
FFMC = 94 DMC = 45 DC = 320
These ratings indicate:
- fine fuels will ignite extremely easily
- fire will involve all fuel levels
- extreme fire behaviour is likely
- 2. The fire behaviour indices (ISI, BUI, FWI) indicate the likely initial spread, total fuel availability, and potential intensity.
Example: 3
ISI = 5 BUI = 120 FWI = 21
These ratings indicate:
- slow initial spread
- high volume of fuel available for combutstion
- potentially high level of fire intensity
- In general terms, a hot, but slow moving fire. The type of fire likely to occur on a windless day in mid-summer after a long dry period.
Example: 4
ISI = 25 BUI = 10 FWI = 21
Note the same FWI as example 3.
These ratings indicate:
- extremely fast initial spread
- low volume of fuel available for combustion
- potentially high level of intensity
- In general, a fast moving fire involving fine fuels only.
Likely to be either:
- a fire in early spring of late autumn when medium and heavy fuels have a moisture content
- and winds are strong, or
- a fire after rain on a day with strong winds
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Explanation taken from http://nrfa.fire.org.nz/fire_weather/fwi_help/values_triggers.htm
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