do not ignite readily from small firebrands although a more intense heat
source, such as lightning, may start fires in duff or punky wood. Fires
in open cured grasslands may bum 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.
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 grasslands will burn briskly and spread rapidly on windy days. Timber
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.
dead fuels ignite readily and fires start easily from most 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 fuels. Fires may become serious and their control difficult unless
they are attacked successfully while small.
|Very High (VH)
start easily from all causes and, immediately after ignition, spread rapidly
and increase quickly in intensity. Spot fires are a constant danger. Fires
burning in light fuels may quickly develop high intensity characteristics
such as long-distance spotting and fire whirlwinds when they burn into heavier
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 fire 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.