**Fire and Aviation Intelligence Terminology**

**Fire Weather:**

Fire weather forecasts are generated by utilizing observations recorded by the federal government’s Remote Automated Weather Stations (RAWS) located throughout the western United States.   RAWS outputs along with documented weather observations made by government personnel each day are retrieved from a national data base and used to compute trend weather forecasts and fire danger indices.  These fire weather forecasts and warnings are often broadcast over the agency’s radio each morning and should be posted on information boards to be utilized by the fire and aviation community.  

Below is a brief description some of the **terms** that are frequently used in the fire weather program:

**FIRE WEATHER ZONES:**

Fire Weather Zones are generally established by each state utilizing geographical and county boundaries to establish zones of forecast responsibility for the National Weather Service.  The forecasts generated from these zones are a combination of the public forecast combined with the parameters obtained from the RAWS data.  It is very important that the fire and aviation resources stationed in an area know what Fire Weather Zone they are operating in each day.  The agency should provide their resource with a map or narrative description of the zone numbers and boundaries.

**RED FLAG PROGRAM:**

The Red Flag Program is a means by which the weather forecaster informs the land management agencies of the possibility of weather elements that could cause extreme fire behavior.  The Red Flag Program generally consists of Fire Weather Watches and Red Flag Warnings which evaluates the combination of weather and fire danger ratings.  Fire Weather Watches and Red Flag Warnings will be headlined in the fire weather narratives and/or may be issued as a separate forecast or statement.   

**Fire Weather Watches:**  Watches are issued when there is reasonable confidence that a red flag event may occur.  The watch is generally issued 12 to 48 hours in advance of the expected weather conditions.

**Red Flag Warnings:**  A red flag warning is used to inform the agencies of the imminent or actual occurrence of the red flag condition. Although specific criteria can be established for each state, a red flag event generally consists of severe fire weather like strong sustained winds, guts, and low humidity, combined with a high fire danger rating.  The warning will be issued immediately when there is a high confidence that severe conditions will occur within the next 24 hours or the criteria is already being met.

**Spot Weather Forecast:**

Spot forecasts are site-specific forecast products issued for wildfires, prescribed burns, search and rescue operations, aerial spraying, etc. when requested by the agency. These forecast are available upon request at any time of day, week or season. Site-specific forecasts are considered one-time requests, and are not routinely updated. 

**Sky/Weather:**  Cloud cover (day or night) expressed as a percentage, and weather descriptors that include rain, snow, showers, thunderstorms, etc. Cloud cover is defined as follows: 

Sunny (day), Clear (night) – less than 6% cloud cover 

Sunny (day), Mostly clear (night) - 6% to 25% cloud cover 

Mostly sunny (day), Partly cloudy (night) - 26% to 50% cloud cover 

Partly sunny (day) / Mostly cloudy (night) - 51% to 69% cloud cover 

Mostly cloudy to Overcast (day or night) - greater than 70% cloud cover

**Wind Speed Ranges Used in Weather Forecasts**

Frontal winds .................................... Too broad a range to be specific.

Foehn ........... 40 to 60 mi/hr common; up to 90 mi/hr reported at 20 ft.

Land breeze ................... 2 to 3 hours after sunset, 3 to 5 mi/hr at 20 ft.

Pacific sea breeze ............................................... 10 to 15 mi/hr at 20 ft.

Up-valley winds 10 to 15 mi/hr, early afternoon and evening at 20 ft.

Upslope winds ................... as high as 4 to 8 mi/hr at midflame height.

Downslope winds .............................. 3 to 6 mi/hr at midflame height.

**20 Foot Winds:**

Surface wind speed and direction (altered by local terrain and surface roughness) that is measured by instrumentation and adheres to standards set by National Wildland Coordination Group (NWCG) for the RAWS program and National Fire Danger Rating System (NFDRS).

**10,000 foot MSL Winds:**

Synoptic scale wind speed and direction representative of winds at roughly 10,000 feet above mean sea level, which are generally unaltered by surface frictional effects. Equivalent to “ridgetop wind”, “wind aloft”, “free-air wind” and “general wind”.

**Ventilation Terminology:**

Basic ventilation information is used in considering the potential for smoke impacts from wildland fires. The following are terms and definitions necessary to understanding ventilation data and values: 

**Mixing Height or Mixing Depth**: 

The height to which relatively vigorous mixing occurs due to heating. Units are in feet above ground level (AGL), with ground level being the elevation above mean sea level (MSL) of the upper-air site. 

**Transport Winds**: A measure of the average rate of the horizontal transport of air within the mixing layer. Units are in knots (1 knot = 1.15 mph). An average wind direction (the direction from which the wind is blowing) is provided. 

**Ventilation**: The product of the mixing height and the transport wind speeds. It is a measure of the volume rate of horizontal transport of air within the mixing layer per unit distance normal to the winds. Units are in knot-feet, though some regulatory entities use meters2/second. Ventilation values are established at a state level and used used for smoke management or regulatory purposes. 

**Lightning Activity Level (LAL):**

The LAL is the expected or observed lightning activity level in the area.  There are six categories:

**LAL 1 –** No thunderstorms.

**LAL 2 –** Isolated thunderstorms. Light rain will occasionally reach the ground. Lightning is very infrequent, 1-5 cloud to ground strikes in a 5 minute period.

**LAL 3 –** Widely scattered thunderstorms. Light to moderate rain will reach the ground. Lightning is infrequent, 6-10 cloud to ground strikes in a 5 minute period.

**LAL 4 –** Scattered thunderstorms. Moderate rain is commonly produced. Lightning is frequent, 11-15 cloud to ground strikes in a 5 minute period.

**LAL 5 –** Numerous thunderstorms. Rainfall is moderate to heavy. Lightning is frequent and intense,  greater than 15 cloud to ground strikes in a 5 minute period.

**LAL 6 –** Same as LAL 3 except thunderstorms are dry (no rain reaches the ground). This type of lightning has the potential for extreme fire activity and is normally highlighted in fire weather forecasts with a Red Flag Warning.

**Haines  Index:**

The Haines Index is a numerical means to indicate the potential for large wildfires to experience extreme fire behavior (crowning, spotting and rapid rates of spread).  It is used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire. It is calculated by combining the stability and moisture content of the lower atmosphere into a number that correlates well with large fire growth. The stability term is determined by the temperature difference between two atmospheric layers; the moisture term is determined by the temperature and dew point difference. This index has been shown to correlate with large fire growth on initiating and existing fires where surface winds do not dominate fire behavior. Stability and dryness are combined into one number for the Hanies Index.  The drier and more unstable the atmosphere, the higher the Haines Index and the potential for extreme fuel driven fire behavior.   *(Keep in mind that Haines Index does not include potential for fire ignition or effects of wind on fire spread.)*

Haines Index classifications are from **2 to 6:**

Haines Index:  **2 or 3**Potential for Large Fire Growth:  **VERY LOW**

Haines Index:  **4**Potential for Large Fire Growth:  **LOW**

Haines Index: **5**Potential for Large Fire Growth: **MODERATE**

Haines Index: **6**Potential for Large Fire Growth: **HIGH**

**Burning Index (BI):**

The Burning Index (BI) is an estimate of the potential difficulty of fire control as a function of how fast and how hot a fire could burn. BI is an NFDRS index relating to the flame length at the head of the fire. BI is It has been scaled so that the BI value divided by 10 predicts the flame length at the head of a fire. For example, a BI of 75 would predict a flame length of 7.5 feet. BI is a function of the Spread Component and the Energy Release Component, and has moderate variability. It is sensitive to fuel models, and can trace seasonal trends reasonably well for models with heavy dead or live components. Because it uses wind and relative humidity, it is also very sensitive to weather observation errors.

**Energy Release Component (ERC)**

ERC is an NFDRS index related to how hot a fire could burn. It is directly related to the 24-hour, potential worst case, total available energy (BTUs) per unit area (in square feet) within the flaming front at the head of a fire.  The ERC can serve as a good characterization of a fire season as it tracks seasonal fire danger trends well. The ERC is a function of the fuel model and live and dead fuel moistures. Fuel loading, woody fuel moistures, and larger fuel moistures all have an influence on the ERC, while the lighter fuels have less influence and wind speed has none. ERC has low variability, and is one of  the best fire danger component for indicating the effects of intermediate to long-term drying on fire behavior.  

ERC charts are primarily used to look at the seasonal trends, a comparison tool against previous years, and as one tool used in determining the geographic area preparedness level. Each chart displays the current year ERC values relative to the average for a 25-year period, the average of the highest values during the same period, and when the values reach the 90th and 97th percentiles. The Charts are not designed to be site specific, they provide only a general picture of how conditions are progressing for the season.  

Generally, ERC charts for different fuel models are available for review on the Geographic Area Coordination Center (GACC) web page under the predictive services section.    

**Fire Behavior:**

Fire behavior is described most simply in terms of fireline intensity (in feet of flame length) and in rate of spread (in chains per hour).

**PREPAREDNESS LEVELS:**

Preparedness levels are established at a local, geographical and national level and are dictated by the burning conditions, fire activity and resource availability.  The primary purpose for developing preparedness plans for geographic and national levels is to help identify the level of wildland and prescribed fire activity and severity of an area and to ensure an appropriated level of readiness is available for responding to existing or potential situations.  Preparedness levels will range from Level 1 through Level 5 for both geographic and national plans.  Level 1 generally represents light to moderate wildland and prescribed fire activity with little or no commitment of national resources.  Level 5 represents major fire activity with a potential to exhaust all agency fire resources.  Preparedness Plans are published annually in the National Mobilization Guide and the specific Geographic Area Mobilization Guides. 

Current preparedness levels are generally posted daily on local, geographical and national situational reports.

**SITIUATION REPORTS:**

Government agencies generate daily situation reports on a local, geographical and national level.  These reports provide the fire and aviation community with important information about the current status of fire and aviation operations in their area.

**Local Level:**  Situation reports generated at a local level record detailed information about current fire danger rating and planning levels for the unit.  They also document the new fire starts as well as providing updates on the large fire activity, and provide information on what resources are committed or available for supporting fire and aviation operations.

**Geographical Level:**  The land management agencies are broken down into 11 Geographical Area Coordination Center areas throughout the United States.  These geographical coordination areas are responsible for combining all the intelligence recorded from the local units within that area and generating a geographical situation report.  This report provides a good overview of the current fire situation including incident management teams that have been mobilized, updates on large fire activity, provides information on the aviation resources that are available for support, and documents the planning level established for the geographic area.

**National Level:**  The national situation reports combines the intelligence information reported from all the geographic areas and produces highlights from the large fires in each area as well as documents the planning level for the nation.

**AVIATION INTERAGENCY INTERIM FLIGHT AND DUTY LIMITATIONS:**

During extended periods of high level of flight activity and fatigue factors, a geographic area may choose to implement interim flight and duty limitations for that area.  The interim flight duty limitations were designed to provide flight crew members with additional hours of uninterrupted rest off duty or an additional day off for each 14 day period.  Aircraft fixed daily rates and special rates will continue to accrue during the extra day off, and availability / unavailability are still computed at 14/14ths.  Interim flight and duty limitations are designated by Phase 1 through Phase 3, and they are published annually in the National Mobilization Guide.