Calculating

Daily Fire Danger Adjective Ratings

for

New York State Forest Rangers

Adjective Rating is a standard fire danger product used to

convey the current fire danger rating in common descriptive

terms.

Adjective Ratings allow fire danger information to be easily understood by fire management personnel, and can be used to convey the relative severity of

the current fire danger situation to the general public.

Table 2-1. Adjective Rating Class Descriptions

Adjective Rating Class and Color Code Class Description

LowGreen

Fuels 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 burn freely a few hours after a rain, but timber fires spread slowly, by creeping or smoldering, and burn in irregular fingers. There is little danger of spotting.

ModerateBlue

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 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.

HighYellow

All fine, 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 HighOrange

Fires start easily from all causes and, immediately after ignition, spread rapidly, increasing 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 fuels.

ExtremeRed

Fires 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 conifer stands may be unmanageable while extreme burning conditions last. Under these conditions, the only effective and safe control action is on the flanks of the fire until weather changes or fuel supply lessens.

Adjective Rating Color Codes and Class Descriptions are standard National Wildfire Coordinating Group (NWCG) Definitions

Fire Danger Rating Areas are geographic areas of similar vegetation, climate, and topography modified by absolute criteria. There is at least one representative RAWS located in each FDRA

Adjective Rating is set daily for each of the 10 Fire Danger Rating Areas

August 28, 2004

How?The Daily Fire Danger Adjective Rating

for each FDRA in New York is calculated from current and historic weather data and fire occurrence records using the National Fire Danger Rating System

(NFDRS).

The daily fire weather data is obtained from the RAWS network,

the historic weather data is obtained from WIMS, and the historic fire

occurrence data is obtained from the Agency.

Historic weather data is obtained from KCFast, a subset of WIMS

The data is entered into a fire analysis program called FireFamily Plus. This

program combines the historic weather and fire data producing an

array of NFDRS outputs such as ERC, BI, KBDI, 1000 hr. fuel moistures, etc.

FireFamily Plus allows selection of fire occurrence data based on Agency criteria. New York uses administrative Regions, Counties, and Towns as

the sub-units that define Fire Danger Rating Areas.

FireFamily Plus allows the fire manager to graphically identify “fire business

thresholds”. These thresholds identify output values that equate to historic fire

occurrence.

Fire business thresholds are unique to each Fire Danger Rating Area and are defined in the Agency’s Fire Danger

Operating Plan.

These threshold values are used to set decision points for adjective rating.

Decision Points!

These threshold values are used to set “decision points” for

adjective rating.

Analysis tools in FireFamily Plus allow the fire manager to edit the selected decision points to fit various local and Agency criteria such as

fuel model, values at risk, fire fighting resources, accessibility, land use parameters, etc.

Example:

Moderate = 15

High = 25

Very High = 30

Extreme = 36

These decision point values are then applied to the seasonality graph of the

particular RAWS.

Seasonality graphs portray the history of a specific NFDRS product over the

record life of the station, and allow the fire manager to track current values and

trends relative to the station history.

The average and maximum value lines provide a quick summary of the stations

NFDRS characteristics!

High

Moderate

Seasonality Graph of a Station’s Weather Data

2004

The seasonality graph is where the NWS NFDRS Point Forecast is used by

combining the current annual trend with the daily forecast.

For example, if today is 8/1, and the point forecast for 8/2 is an ERC of 25,

we know we will be at or least continuing to trend toward High fire

danger.

High

Moderate

Seasonality Graph of ERC for the Schuyler Falls RAWS

2004

25

NFDRS Point Forecast Value

That’s it!

Questions?

Comments?