NTFB - Assumptions and Limitations

Despite the strengths of WFDSS Near-Term Fire Behavior (NTFB), like any model, it has its limitations. The following list includes some of the more important caveats to keep in mind when using the program for management and planning decisions:

1. Weather is difficult to predict; fire forecasts are only as good as the input data. Use caution when running NTFB beyond three days as, after that timeframe, it becomes more probable that the actual weather may not match the forecast data. Weather data from the RAWS and the forecast data need to be critiqued and potentially adjusted by the Fire Behavior Specialist (FBS).
2. NTFB incorporates existing models for surface fire, spotting, post-frontal combustion and fire acceleration (among others), and all of the limitations and assumptions of those models are present. Many of these models are a part of the desktop program, BEHAVE, which is commonly described as having a range that can 'under-predict by half or over-predict by double'.
3. When using the Scott and Burgan (2005) 40 fuel models, mistakes or incorrect assumptions with live fuel moisture transfer can result in faulty model outputs. 
4. Fires are assumed to burn as ellipses under uniform conditions. This assumption allows the model to make a close approximation of fire growth, however, real conditions are clearly more complex and heterogeneous than any fire model.
5. Multiple fires and fire behavior calculated at vertices are assumed to burn independently of each other (there is no interaction between fire fronts).
6. Fire growth predictions tend to worsen over time because errors begin to compound.
7. Spotting from torching trees will likely under-predict spotting from active crown fire, particularly in relation to distance.
8. NTFB cannot assume the impacts (success or failure) of active suppression actions that are being undertaken. Analysts can add barriers to represent fireline or a cold fire perimeter, but cannot incorporate the impacts of aerial retardant or water, blacklining, burnouts or 'stalling' actions. Alternatively, modeled fire that was not able to cross a barrier in NTFB will not subsequently smolder or creep across it at a later time as live fire can under real world conditions.
9. As with all models, the quality of the outputs from WFDSS STFB depends on the quality of the inputs. If the landscape data, RAWS data, or forecast data used are inadequate, the resulting fire behavior outputs will be questionable. It is important to critique and  modify as needed,  the fuels data, as well as the RAWS and forecast data before using WFDSS NTFB results in support of wildland fire decision-making. 

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Last updated on 1/28/2019 12:25:07 PM.

In This Section WFDSS Near-Term Fire Behavior Analysis (NTFB)

See Also NTFB - What it is NTFB - What it needs (inputs) NTFB - What it does (outputs) NTFB - What it means (interpretation) Analyst-Assisted NTFB - Why use it (potential uses)

Reference Field Descriptions Glossary Resources Spatial Data Reference Landscape Data Source Reference Relative Risk Reference Organization Assessment Reference Fire Behavior Reference About the WFDSS Decision Editors