2. Lesson Objectives
• List three elements used to
determine fire danger rating.
• List the five ‘standard’ fire danger
rating levels.
1G-02-P101-EP
3. Introduction
• Fire Prevention/Mitigation Specialists
should constantly be aware of the fire
weather conditions and forecasts.
The fire danger affects most of what
these specialists do on a day-to-day
basis.
1G-03-P101-EP
4. Introduction
• This is an overview of the fire danger
ratings, and the NFDRS and is not
intended to be a lesson in fire
behavior.
1G-04-P101-EP
5. The National Fire Danger Rating
System
• Determines fire danger in the area
• Managers may impose
restrictions/closures
• Pre-position resources
• Make fire management decisions
1G-05-P101-EP
7. • The importance of the basic aspects of
fire behavior – ease of ignition, rate of
spread, and the rate of combustion –
cannot be over emphasized since they
dictate what is needed to control a fire.
1G-07-P101-EP
8. • Fire behavior components are principle
keys to fire danger rating.
• It sets the numbers that managers can
use for limiting use, setting restrictions,
and for fire planning.
1G-08-P101-EP
9. Understanding Fire Danger
• Fire Danger is a description of the
combination of both constant and
variable factors that affect the
initiation, spread, and difficulty to
control a wildfire.
1G-09-P101-EP
10. Understanding Fire Danger
• Since 1974, five Adjective Fire
Danger levels have been used in
public information and signing.
Recently, several areas have added
another administrative element. This
is not the normal application, and is
used here as information only.
1G-10-P101-EP
11. Fire Danger Level
• Fire starts are unlikely. Weather and
fuel conditions will lead to slow fire
spread, low intensity, and relatively
easy control with light mop-up.
Controlled burns can usually be
executed with reasonable safety.
1G-11-P101-EP
12. Fire Danger Level
• Some wildfires may be expected.
Expect moderate flame length and rate
of spread. Control is usually not difficult
and light to moderate mop-up can be
expected.
1G-12-P101-EP
13. Fire Danger Level
• Wildfires are likely. Fires in heavy,
continuous fuel will be difficult to control
under windy conditions. Control through
direct attack may be difficult but
possible, and mop-up will be required.
1G-13-P101-EP
14. Fire Danger Level
• Fires start easily and may spread faster
than suppression resources can travel.
Flame lengths will be long with high
intensity, making control very difficult.
Suppression and mop-up will require an
extended and very thorough effort.
1G-14-P101-EP
15. Fire Danger Level
• Fires will start and spread rapidly. Every
fire start has the potential to become
large. Expect extreme, erratic fire
behavior.
1G-15-P101-EP
16. Fire Danger Level
• Information only. This element is being
used in several areas as a management
and public relations tool. When
conditions are critical, (major fires,
extreme weather forecasts, resource
drawdown, natural disasters, etc.) this
level is used.
1G-16-P101-EP
17. Fundamentals of Fire Danger
Fuel Moisture
• Live Fuels
• Dead Fuels
1G-17-P101-EP
24. Lower Atmosphere Stability
Haines Index
• 2 – Very low potential
• 3 – Very low potential
• 4 – Low potential
• 5 – Moderate potential
• 6 – High potential
1G-24-P101-EP
25. Energy Release Component
• Based on the estimated potential
available energy released per unit
area in the flaming front
• Variations caused by changes in fuel
moisture contents
• Derived from predictions of rate of
heat release
1G-25-P101-EP
26. Energy Release Component
• Defined as the potential available
energy per square foot of flaming fire
at the head of the fire and is
expressed in British Thermal Units
(BTU)
1G-26-P101-EP
27. Ignition Component
• The ignition component is a number
that relates to the probability that a
fire will result if a firebrand is
introduced into a fine fuel complex.
1G-27-P101-EP
28. Spread Component
• The spread component integrates the
effects of wind and slope with fuel
bed and fuel particles to compute the
forward rate of spread at the head of
the fire. Output is unit of feet per
minute.
1G-28-P101-EP
29. Summary and Review Lesson
Objectives
• List the elements used to determine
fire danger rating.
• List the five ‘standard’ fire danger
rating levels.
1G-29-P101-EP
