Current Conditions - Library
Fire Danger Ratings
A Fire Danger Rating level takes into account current and antecedent weather,
fuel types, and both live and dead fuel moisture (Deeming and others 1977, Bradshaw and others 1984 ).
The adjective class rating (see table below) is a method
of normalizing rating classes across different fuel models, indexes,
and station locations. It is based on the primary fuel model cataloged for the
station, the fire danger index selected to reflect staffing levels,
and climatological class breakpoints. This information is provided
by local station managers. About 90% use the Burning Index (BI);
others use Energy Release Component (ERC). Staffing class breakpoints are set by
local managers from historical fire weather climatology.
- The color code is green.
Fuels do not ignite readily from small firebrands, although
a more intense heat source, such as lightning, may start
many fires in duff or punky wood. Fires in open cured grassland
may burn freely a few hours after rain, but woods fires spread
slowly by creeping or smoldering, and burn in irregular fingers.
There is little danger of spotting.
- The color code is blue.
Fires can start from most accidental causes, but with the
exception of lightning fires in some areas, the number of
starts is generally low. Fires in open-cured grassland will
burn briskly and spread rapidly on windy days. Woods fires
spread slowly to moderately fast. The average fire is of
moderate intensity, although heavy concentrations of fuel,
especially draped fuel, may burn hot. Short-distance spotting
may occur, but is not persistent. Fires are not likely to
become serious, and control is relatively easy.
- The color code is yellow.
All fine dead fuels ignite readily and fires start easily
from just causes. Unattended brush and campfires are likely
to escape. Fires spread rapidly and short-distance spotting
is common. High-intensity burning may develop on slopes,
or in concentrations of fine fuel. Fire may become serious
and their control difficult, unless they are hit hard and
fast while small.
- The color code is red.
Fires under extreme conditions start quickly, spread furiously,
and burn intensely. All fires are potentially serious. Development
into high-intensity burning will usually be faster and occur
from smaller fires than in the very high danger class. Direct
attack is rarely possible, and may be dangerous, except immediately
after ignition. Fires that develop headway in heavy slash
or in conifer stands may be unmanageable while the extreme
burning condition lasts. Under these conditions, the only
effective and safe control action is on the flanks until
the weather changes or the fuel supply lessens.