Fire Behavior
Despite a clear link between drought and wildfire, there is currently a lack of information for stakeholders at the regional and local levels for improved wildfire risk management using drought early warning information. Fire managers and other specialized fire professionals, such as Incident Meteorologists, will increasingly need to effectively use drought information in forecasts of fire behavior at fire incidents, and in long-term planning (i.e., seasonal fire potential outlooks) as the climate continues to warm along with shifts in the timing and duration of fire seasons.
This webinar highlights recent efforts to incorporate drought-wildfire linkages into the National Integrated Drought Information System (NIDIS) California-Nevada Drought Early Warning System. Research has shown that drought indices which are both multi-scalar and incorporate evaporative demand are most strongly correlated to fuel moisture. Testing of the Evaporative Demand Drought Index (EDDI) was conducted by Predictive Services in Northern California during the 2018 fire season. Web tools have been developed (and some that are still in development) to access EDDI, other drought indices, and remote sensing data (often with global coverage) that can potentially benefit wildland fire management in Alaska. Focus will be on EDDI tools developed at NOAA’s Physical Science Division and Climate Engine (app.climateengine.org) developed jointly between the Desert Research Institute and University of Idaho.
Presented by Dan McEvoy, Desert Research Institute and Western Regional Climate Center, Reno, NV.
A rotor-wing unmanned aerial system (UAS) hovering above a fire provides a static, scalable sensing platform that can characterize terrain, vegetation, and fire coincidently. This study presents methods for collecting consistent time-series of fire rate of spread (RoS) and direction in complex fire behavior using UAS-borne NIR and Thermal IR cameras. Using a hybrid temperature-gradient threshold approach with data from two prescribed fires in dry conifer forests, the methods characterize complex interactions of observed heading, flanking, and backing fires accurately.
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Wildland firefighters in the United States are exposed to a variety of hazards while performing their jobs in America’s wildlands. Although the threats posed by vehicle accidents, aircraft mishaps, and heart attacks claim the most lives, situations where firefighters are caught in a life-threatening, fire behavior-related event (i.e. an entrapment) constitute a considerable danger because each instance can affect many individuals. In an attempt to identify the scope of understanding of the causes of firefighter entrapments a review of the pertinent literature and a compilation and synthesis of existing data were undertaken.
The Hot-Dry-Windy Index (HDW) was designed to help users determine which days are more likely to have adverse atmospheric conditions that make it more difficult to manage a wildland fire. It combines weather data from the surface and low levels of the atmosphere into a first-look product.
HDW was designed to be very simple – a multiplication of the maximum wind speed and maximum vapor pressure deficit (VPD) in the lowest 50 or so millibars in the atmosphere. Because HDW is affected by heat, moisture, and wind, seasonal and regional variability can be found when comparing HDW values from different locations and times.
Linear fuel breaks may help reduce wildfire intensity and spread, and at the same time improve firefighting effectiveness, but their ecological impacts may include habitat loss and fragmentation, as well as facilitation of species movement. There is very little peer‐reviewed science available to inform land managers about the ecological effects of fuel breaks. As such, land managers may face trade‐offs with uncertain outcomes: either substantially alter habitats with fuel breaks to potentially minimize wildfire impacts or risk increased habitat loss and degradation from wildfire. The Great Basin region of the western US offers an opportunity to better understand the relative costs and benefits of fuel breaks, and to identify key knowledge gaps
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On average, one third of the area burned by predicted wildfires was non-local, meaning that the source ignition was on a different land tenure. Land tenures with smaller parcels tended to receive more incoming fire on a proportional basis, while the largest fires were generated from ignitions in national parks, national forests, public and tribal lands. Among the 11 western States, the amount and pattern of cross-boundary fire varied substantially in terms of which land tenures were mostly exposed, by whom and to what fire sizes. We also found spatial variability in terms of community exposure among States, and more than half of the predicted structure exposure was caused by ignitions on private lands or within the wildland-urban interface areas. This study addressed gaps in existing wildfire risk assessments, that do not explicitly consider cross-boundary fire transmission and do not identify the sources of fire. The results can be used by State, Federal, and local fire planning organizations to help improve risk mitigation programs.
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Of our estimated 3.7 Mkm2 of rangeland in the continental US and Alaska, an average of 38 000 km2 burned per year between 2008 and 2017. To highlight the role of soils in fire ecology, we present 1) a conceptual framework explaining why soil information can be useful for fire models, 2) a comprehensive suite of literature examples that used soil property information in traditional soil survey for predicting wildfire, and 3) specific examples of how more detailed soil information can be applied for pre- and post-fire decisions.
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This study reviews published studies on reburns in fire-adapted ecosystems of the world, including temperate forests of North America, semi-arid forests and rangelands, tropical and subtropical forests, grasslands and savannas, and Mediterranean ecosystems. To date, research on reburns is unevenly distributed across the world with a relative abundance of literature in Australia, Europe and North America and a scarcity of studies in Africa, Asia and South America. This review highlights the complex role of repeated fires in modifying vegetation and fuels, and patterns of subsequent wildfires. In fire-prone ecosystems, the return of fire is inevitable, and legacies of past fires, or their absence, often dictate the characteristics of subsequent fires.
The Reburn Project was motivated by a need to better understand wildfires as a type of fuel reduction treatment and to assess the impacts of fire suppression on forested landscapes. The original JFSP task statement (Influence of past wildfires on wildfire behavior, effects, and management) was created to inform the National Cohesive Wildland Fire Management Strategy and to address how past wildfires influence subsequent wildfire spread and severity as well as to evaluate how past wildfires may support different fire management strategies. Our study focused on three study areas, located in the inland Pacific Northwest, central Idaho and interior British Columbia. Each study area was centered on a recent, large wildfire event in montane, forested landscapes.We first evaluated fire-on-fire interactions between past wildfires and subsequent large fire events (see Stevens-Rumann et al. 2016). Next, we created a landscape fire simulation tool that allowed us to explore the impact of fire management on the patterns of forest vegetation and fuels across landscapes. To do this, we created an iterative tool that uses historical ignition and weather data to evaluate potential burn mosaics compared to actual pre-wildfire landscapes under different wildfire management strategies.
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The Climate Forecast System Reanalysis (CFSR) is used to provide the meteorological data for calculating the indices. Our results indicate that HDW can identify days on which synoptic-and meso-alpha-scale weather processes can contribute to especially dangerous fire behavior. HDW is shown to perform better than the HI for each of the four historical fires. Additionally, since HDW is based on the meteorological variables that govern the potential for the atmosphere to affect a fire, it is possible to speculate on why HDW would be more or less effective based on the conditions that prevail in a given fire case. The HI, in contrast, does not have a physical basis, which makes speculation on why it works or does not work difficult because the mechanisms are not clear.