AREA-WIDE CHARTS	View Individual Station Charts

FUEL MODEL	ARIZONA	NEW MEXICO	SOUTHWEST AREA
A Burning Index (Western Grass (FM-1))
C Burning Index (Open Pine w/Grass (FM-2))
G Energy Release Component (Closed, short-needle conifer (FM-10))
K Energy Release Component (Light Slash (FM-11))

What is the Burning Index (BI)?

The Burning Index (BI) is a number related to the contribution of fire behavior to the effort of containing a fire. It is derived from the spread and energy release components (Spread Component and Energy Release Component). The rate of fire spread and the energy released in the flaming zone, considered together, are the measns of rating the difficulty of containment. The Bi is liinearly reated to the length of flames at the head of the fire. It is calculated from the SC and ERC using the relationships originally developed by Byram for calculating flame length (Byram 1959).

What is the Energy Release Component (ERC)?

The Energy Release Component (ERC) is based on the estimated potential available energy released per unit area in the flaming front of a fire. The day-to-day variations of the ERC are caused by changes in the moisture contents of the various fuel classes, including the 1,000 hour timelag class.  The ERC is derived from predictions of (1) the rate of heat release per unit area during flaming combustion and (2) the duration of flaming.

How are the Charts above derived?

The charts above, in general, are use by wildland fire managers to determine the potential that may be expected from a wildland fire. The charts are derived from data collected at 12 Automated Weather Stations (AWS) strategically located throughout the Southwest Area.  The 12 stations are:  

1.	Tusayan	020207	Kaibab NF
2.	Flagstaff	20209	Coconino NF
3.	Lakeside	20303	Apache-Sitgreaves NF's
4.	Globe	20601	Tonto NF
5.	Saguaro	20212	Coronado NF
6.	Jemez	290702	Santa Fe NF
7.	Grants	291302	Cibola NF
8.	Beaverhead	292001	Gila NF
9.	Mayhill	293002	Lincoln NF
10.	Iron Springs	20501	Prescott NF
11.	Mountainair	291501	Cibola NF
12.	Truchas	290210	Carson NF

In the Southwest Area, the Charts are averaged over 3-day periods.  They are primarily used to look at the seasonal trends, a comparison tool against previous years, and as one tool used in determining the Area preparedness level.

The Charts compare the current year BI or ERC values against the average for a 25-year period   and the average of the highest values during the same period. The Charts are not designed to be site specific, they provide only a general picture of how conditions are currently and how the season is progressing in the Southwest. Units throughout the SWA produce their own local, site specific chart(s).

How are the Charts used in preparedness?

All wildland protection agencies are directed to protect life, property, and natural resources entrusted to them. These requirements dictate strict attention be paid to the availability and use of suppression resources. To this end, a system has been established to determine the preparedness levels that all wildland fire agencies within the SWA will use.

The Charts above are only one of the components used in determining the SWA preparedness level. Other components that must be considered include; (1) current and long range forecasted weather affecting current and forecasted fire behavior/potential, (2) resource committments to incidents, (3) individual agency fire reports, (4) National Preparedness Level, (5) air quality considerations, and (6) fire suppression resource availability.

The breakpoints in which the ERC Curve is used to assist in determining the area preparedness level are indicated by lines drawn horizontally (i.e. PL-2, PL-3, PL-4) on the chart.  The 90th corresponds to the "very high" adjective reading and the 97th percentile corresponds to the "extreme" adjective reading.

The Charts are generated using Fire Family Plus and the National Fire Danger Rating System.