FAQs for Automated BFB and STFB

These Questions and Answers are intended to provide an overview of the automated version of WFDSS Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) applications. For more detailed information about these applications, as well as their assumptions and limitations, please see the following documents on WFDSS Home page > Related Resources > Fire Behavior:

What is the procedure for setting up and running Basic Fire Behavior (BFB) and Short Term Fire Behavior (STFB) analyses?

For instructions on how to set up and run BFB and STFB analyses, see “Basic and Short-Term Fire Behavior (PDF - 7.9 MB)”, also found on the WFDSS Home page > Training > Webinars and Other Elearning. Or, you can go to the Running an Automated Basic Fire Behavior or Running an Automated Short-Term Fire Behavior in the online help.

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Last updated on 8/17/2017 11:35:53 AM.

What is the purpose of the Automated Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB), and how can they be used?

The automated BFB and STFB applications within WFDSS are designed for use by non-fire behavior specialists to quickly obtain outputs for a fire area using historic or forecast weather at a given wind speed and direction. In these models, weather and wind inputs do not change during the analysis; they represent only a snapshot in time. These analyses can be run and viewed by the Incident Author, Owner, or anyone granted Incident privileges. The fire behavior outputs from these applications can provide insight into potential fire spread and fire behavior, however, because they are computer generated without analyst involvement, they should be utilized only as a broad general overview. If very specific questions need to be answered to make important planning decisions an Analyst Assisted fire behavior model should be utilized.

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Last updated on 8/17/2017 11:36:02 AM.

How valid are the fire behavior results from Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) and can they be used to support fire management decisions?

As with all models, the quality of the outputs are relative to the quality of the input data. The automated versions of BFB and STFB use default settings for weather and landscape that might not be the best representation of actual conditions. Before using BFB and STFB outputs to support decision-making, critique and assess the results to decide how well they represent reality. For better model output, request an analyst-assisted BFB and STFB.

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Last updated on 8/17/2017 11:36:06 AM.

How does the Automated version of WFDSS Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) differ from the desktop version of FlamMap 3.0?

The differences are numerous and significant. Please see “Comparison of FLAMMap and Automated WFDSS Basic and Short-term Fire Behavior.pdf”, also available on the WFDSS Home site > Related Resources > Fire Behavior for a comprehensive comparison.

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Last updated on 8/17/2017 11:36:13 AM.

What is the difference between WFDSS Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB)?

WFDSS provides most of the inputs (including forecasted weather) for both applications. BFB calculates and maps “snapshot in time” fire behavior outputs for an entire user-defined landscape extent. STFB calculates the "snapshot fire behavior and the fire spread (arrival time) results, as well as the fire’s major paths from a single ignition point.

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Last updated on 8/17/2017 11:36:18 AM.

Can local landscape data be uploaded into WFDSS for use in Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB)?

Yes. In the landscape section of an analyst-assisted fire behavior analysis, you can upload LCP files. However, you can only do an analysis for the extent of the LCP you upload. For automated BFB and STFB, the system uses the National LANDFIRE data layer.

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Last updated on 8/17/2017 11:36:22 AM.

What landscapes can be used for WFDSS Analyst-Assisted Fire Behavior Models?

WFDSS uses the aspect, slope, elevation, fuel model, canopy cover, canopy base height (CBH), canopy bulk density (CBD), and stand height layers to a create landscape file that displays fuels, topography and canopy information simultaneously. Landscape data can be viewed for any point on a map display by clicking the Info sub-tab > selecting the tool > and then clicking on the landscape. The default Landscape Data Source for incidents is the most current source available, but this can be changed for an incident on the Incident Information tab.

Landscape data in WFDSS is sourced from LANDFIRE and a multi-partner wildland fire and wildland fuel mapping project in the state of California. All values are measured with the metric system:

Variable	Unit of Measure
aspect	degrees
slope	degrees
elevation	meters
canopy base height	meters
canopy bulk density	kg/m3
canopy cover	percent
stand height	meters

The California landscape 2010 data set is an annual, multi-partner wildland fire and wildland fuel mapping project within the state of California. The California fuels data are supported by the California Fire and Resource Assessment Program (FRAP), US Department of Agriculture (USDA) Forest Service Region 5 Fire and Aviation Management, the US Department of Interior (US DOI) Bureau of Land Management and DOI National Park Service. California fuel data tasks are completed by the USDA Region 5 Remote Sensing Lab.

For more details, got to Landscape Data Source Reference.-----------
Last updated on 8/17/2017 11:36:28 AM.

How do you define your landscape analysis area (landscape extent), and how large should it be when doing Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

You draw a rectangle on the map using the Landscape Extent icon on the Situation Assessment map. Since you should only be concerned with fire behavior characteristics or fire spread for a short time, you do not need to draw a large analysis area. Typically, an extent of 5-6 miles per side should suffice. If you run your STFB analysis and it seems too small, you can always re-draw the landscape extent. Making your landscape extent too large will slow the process time and tie up server time, thereby delaying other's analyses.

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Last updated on 8/17/2017 11:36:32 AM.

What resolution is used for the landscape data in Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

The resolution of the landscape used for BFB and STFB analyses depends on the landscape extent drawn by the user. For extents that are 10 miles by 10 miles (100 square miles) or smaller, 30-meter resolution is used. For landscapes that are larger than 100 square miles and smaller than 400 square miles, the resolution is generally 60 meters. For extents that are 20 miles by 20 miles, the resolution is 90 meters. The maximum landscape extent allowed is 900 square miles (30 miles by 30 miles), and the resolution is automatically scaled to 120 meters.

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Last updated on 8/17/2017 11:36:37 AM.

Can the landscape data be modified for Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

In the automated version of BFB and STFB, you cannot modify the landscape data. The Analyst-assisted versions of BFB and STFB have a Landscape Editor (the same as that used in FSPro) to make modifications to the landscape data.

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Last updated on 8/17/2017 11:36:42 AM.

Can the user choose which RAWS to use for weather and wind data for Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

In the current automated version of BFB and STFB, you cannot choose which RAWS to use. You can only use the WFDSS-selected RAWS. In the Analyst-assisted versions of BFB and STFB, the fire behavior specialist can select a RAWS from a list, as long as it has the requisite observations.

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Last updated on 8/17/2017 11:36:46 AM.

How does WFDSS Select the RAWS for Automated Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) Analyses?

WFDSS selects the RAWS by doing the following:

Identifying the center of the landscape extent
Calculating the distance from the center to the nearest RAWS using a horizontal/vertical (elevation) algorithm
Ranking the stations
Selecting the station that is the “closest” and has weather data requisite for conditioning (7 days of hourly weather observations)

The RAWS that is selected for the automated WFDSS models cannot be changed. If a different RAWS station is desired an analyst assisted model must be used.

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Last updated on 8/17/2017 11:36:50 AM.

What are the RAWS data used for in Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

WFDSS BFB and STFB automatically conditions fuels by using the previous 7 days of weather observations from the RAWS. Dead fuel moistures are calculated for every cell in the analysis area using these RAWS data; however, in the Automated versions, the user cannot modify the observations to better reflect the weather in the area of the fire.

How does fuel moisture conditioning work in Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB)?

The user chooses a date and time for which they want the analysis to start. WFDSS looks back for the last 7 + days (up to 14 days) to obtain the necessary RAWS observations for automatically conditioning the dead fuels and determining dead fuel moisture values as of the analysis date and time. The moisture values are based on the weather, as well as the cell's aspect, elevation, and canopy cover. Those fuel moistures are then used to calculate fire behavior characteristics. To see how to view the observations used in fuel conditioning, refer to How to View WFDSS Automated Fire Behavior Inputs.

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Last updated on 8/17/2017 11:37:14 AM.

How do Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) get forecasted weather and can these data be changed?

In WFDSS BFB and STFB, forecasted weather is obtained from the National Digital Forecast Data (NDFD). NDFD uses RAWS location to derive forecasted weather data. These data can not be modified by the user in the automated version.

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Last updated on 8/17/2017 11:37:10 AM.

How does Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) get forecasted winds, and can these data be changed?

In WFDSS BFB and STFB, forecasted wind speed and direction values are obtained from the National Weather Service (NWS) Forecast data.

To remain consistent with the current and historic observations, the forecast from the grid cell that contains the RAWS station is used to obtain the weather inputs. Both the wind speed and wind direction values CAN be modified by the user.

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Last updated on 8/17/2017 11:37:06 AM.

Do the Automated Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) Applications use Gridded Winds?

Yes. The wind speed and direction values are used as inputs for WindNinja to create gridded winds at 30-meter resolution. Wind speed and direction values are automatically populated with NDFD data or WIMS (RAWS) data depending on if the analysis is being made for the future or the past respectively. The user can enter their own values if desired. The wind speed value is used as an average velocity across the entirety of the landscape (as defined by the user when drawing an analysis extent). Gridded wind speed inputs will be increased over ridges and decreased in valleys and the wind direction input will change based on the influence of underlying terrain.

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Last updated on 8/17/2017 11:37:00 AM.

What fuel moisture values are used in the Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) applications?

Dead fuel moisture values are calculated by NFDRS and then conditioned based on each cell’s aspect, elevation, and canopy cover, as well as the previous 7 days of RAWS weather data.

BFB and STFB live fuel moisture values are calculated using the Growing Season Index (GSI) and inputs from the selected RAWS. These values cannot be modified in the automated version of BFB and STFB. However, they can be viewed (see Viewing WFDSS Automated Fire Behavior Inputs). In the analyst-assisted versions of BFB and STFB, the fuel moistures can be changed under the initial fuel moisture section. The calculated live woody and herbaceous moisture, in particular, may require an analyst to make edits to better reflect real world values. Foliar moisture content is set to a default value of 100%, and this cannot be changed in the automated BFB and STFB. In the analyst-assisted versions, foliar moisture can be set from 70-140%.

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Last updated on 8/17/2017 11:37:23 AM.

How do you locate the fire ignition to do a Short-Term Fire Behavior (STFB) analysis?

In the automated version of WFDSS STFB, the user can input a latitude/longitude for the ignition, or zoom to a location and create an ignition point by clicking the location on the WFDSS map. Only point locations can be used. In the Analyst-Assisted version, the fire behavior specialist can upload shapefiles of the point fire location or fire perimeters to use as ignition files.

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Last updated on 8/17/2017 11:37:28 AM.

Is spread by spotting incorporated in WFDSS Short-Term Fire Behavior (STFB)?

Yes, spread by spotting has been incorporated in STFB.

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Last updated on 8/17/2017 11:37:32 AM.

What crown fire calculation method is used in Short-Term Fire Behavior (STFB)?

WFDSS uses the Finney (1998) crown fire calculation method for the automated BFB and STFB. For analyst-assisted analyses, you can choose either Finney 1998 or Scott and Reinhardt 2001 as the crown fire method.

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Last updated on 8/17/2017 11:37:40 AM.

What is the Date and Time used for in Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses?

The automated BFB uses the start date and time (and the previous 7 days of weather) to determine dead fuel moisture values and calculate fire behavior characteristics for that “snapshot in time”.

The automated STFB uses the start date and time in the same way, but in addition, it uses that data as the beginning of the fire spread simulation.

For the analyst assisted versions of BFB and STFB, the analysis date and hour can be set by the analyst.

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Last updated on 8/17/2017 11:37:45 AM.

What is a burn period in Short-Term Fire Behavior (STFB) and why do you need it?

In STFB, the burn period is the number of hours, per operational period, that will be used for the fire spread simulation. Because the STFB model uses only one set of fuel moisture and wind (speed and direction) conditions for the entire simulation, it is important to choose the burn period carefully.

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Last updated on 8/17/2017 11:37:49 AM.

How many burn periods can be selected when running Short-Term Fire Behavior (STFB)?

The model allows up to 3 burn periods; however, it is crucial to keep in mind that all environmental conditions (fuel moistures, wind speed, and wind direction) are held constant for the duration of the simulation. Therefore, the user should carefully consider how many hours should be used per burn period and how many burn periods are appropriate. You might want to choose to simulate only one or two burn periods because, in reality, fuel moistures, wind directions, and wind speeds would not be expected to remain constant for very long.

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Last updated on 8/17/2017 11:37:54 AM.

What output results are available when Basic Fire Behavior (BFB) is run and what are the units for each output?

BFB provides many of the same fire behavior outputs as are available in BEHAVE (and BehavePlus). Below are the outputs available in WFDSS BFB and their units:

Output	Display Units
Flame Length	meters or feet
Fireline Intensity	kilowatts per meter (kW/m) or BTU per ft per sec (BTU/ft/sec)
Rate of Spread	meters per minute (m/min) or Chains per Hour or Miles per Hour
Heat per Unit Area	kilojoules per meter squared (kJ/m2 )
Crown Fire Activity	0 (no fire), 1 (surface fire), 2 (torching), 3 (active crown fire)
Maximum Spread Direction	radians

WFDSS BFB also calculates the following environmental outputs:

Output	Display Units
1-hour fuel moisture	fraction (e.g., 0.06 = 6%)
10-hour fuel moisture	fraction (e.g., 0.18 = 18%)
Solar radiation	watts per meter squared (W/m2 )

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Last updated on 8/17/2017 11:37:58 AM.

Can the Basic Fire Behavior (BFB) or Short-Term Fire Behavior (STFB) output legends be changed; for instance, can the classes or colors be changed by the user?

No. In the automated version of WFDSS BFB and STFB, neither the classes nor the color choices can be changed.

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Last updated on 8/17/2017 11:38:03 AM.

Can Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses results be saved and downloaded to GIS?

No. The results cannot be saved or downloaded; they can only be displayed within WFDSS. However, the user can save image captures within the application to be used in the Decision Document.

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Last updated on 8/17/2017 11:38:34 AM.

Can the Basic Fire Behavior (BFB) and Short-Term Fire Behavior (STFB) analyses be saved?

Automated analyses are available for an incident for 20 days, and then they are automatically deleted. The analyst-assisted runs remain with the incident in perpetuity.

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Last updated on 8/17/2017 11:38:29 AM.

When will the Farsite (near-term fire behavior analysis) be available?

It's available now and is called Near-Term Fire Behavior.

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Last updated on 8/17/2017 11:38:15 AM.