Fire Behavior

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Marshall Fire: Facilitated learning analysis

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On a dry winter morning between Christmas and New Year’s Eve 2021, the communities in Boulder County braced for the wind. The area lies at the base of the Front Range, made up of flat-topped mesas and open grasslands where creek bottoms are lined with cottonwood trees. On the outskirts of the communities are scattered homes and ranchettes. Farther east are established neighborhoods with mature landscaping and newer subdivisions sparsely planted with shrubs and ornamental hardwoods. Green corridors and trails run through the area.

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Use of drones for wildfire mitigation, operations, modeling, and research directions

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Increases in large wildfire driven nighttime fire activity observed across the conterminous US

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This presentation discusses the results of 17 years of active fire data from Moderate Resolution Imaging Spectroradiometer (MODIS) to characterize the daytime and nighttime dynamics of wildfires across the continental US. Whereas daytime fire activity was widely detected regardless of fire type, nighttime fire activity was mainly detected inside wildfires and particularly within large wildfires in the western US. The analysis also found that as fuels dry, there is an increase in larger and more intense wildfires with higher chances that fire activity will persist overnight. Results indicate that increasing trends in nighttime wildfire activity have coincided with increasing wildfire sizes. Nighttime fire activity already poses additional risks to firefighters and communities, and this presentation discussed the probability that projected increases in the frequency of large wildfires will be accompanied by increases in the extent and intensity of nighttime fire activity.

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Modeling fire spread in sagebrush steppe using FARSITE: Improving input data and simulation accuracy

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Using RAP to inform pre-fire FBFM selection increased the accuracy of FARSITE simulations compared to parameterization with the standard LANDFIRE FBFM maps, in sagebrush steppe. Additionally, the crosswalk method appeared to have regional generalizability. Flanking and backfires were the primary source of disagreements between simulated and observed fire spread in FARSITE, which are sources of error that may require modeling of lateral heterogeneity in fuels and fire processes at finer scales than used here.

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Probabilistic wildfire risk estimates for individual real estate parcels for the contiguous US

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Historical wildfire ignition locations and NOAA’s hourly time series of surface weather at 2.5 km resolution are used to drive ELMFIRE to produce wildfire hazards representative of the 2022 and 2052 conditions at 30 m resolution, with the future weather conditions scaled to the IPCC CMIP5 RCP4.5 model ensemble predictions. Winds and vegetation were held constant between the 2022 and 2052 simulations, and climate change’s impacts on the future fuel conditions are the main contributors to the changes observed in the 2052 results. Non-zero wildfire exposure is estimated for 71.8 million out of 140 million properties across CONUS. Climate change impacts add another 11% properties to this non-zero exposure class over the next 30 years, with much of this change observed in the forested areas east of the Mississippi River. “Major” aggregate wildfire exposure of greater than 6% over the 30-year analysis period from 2022 to 2052 is estimated for 10.2 million properties. The FSF-WFM represents a notable contribution to the ability to produce property-specific, climate-adjusted wildfire risk assessments in the US.

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2020 fire season: An eye opener but not a fluke

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2020 was a record year for wildfires in recent history, though the area burned was close to estimates of pre-suppression burning. We should expect more of these types of fire seasons in the future. Much of the burning was destructive rather than restorative and impacts to humans were severe.

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Evidence for lack of a fuel effect on forest and shrubland fire rates of spread under elevated fire danger conditions: Implications for modelling and management

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This review and analysis of the relevant scientific literature on the subject suggest that fuel characteristics have a gradual diminishing effect on the rate of fire spread in forest and shrubland fuel types with increasing fire danger, with the effect not being observable under extreme fire danger conditions. Empirical-based fire spread models with multiplicative fuel functions generally do not capture this effect adequately. The implications of this outcome on fire spread modelling and fuels management are discussed.

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Why fires are climbing higher than ever before due to increased western aridity

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Climate-driven changes in global temperatures and aridity are directly correlated with the decreasing interval between high-elevation fires. Fire activity is increasingly disproportionate at higher elevations than that of lower elevation forests in the Western United States. Studies documented an upslope advance of high-elevation fires of roughly 7.6 m (25 ft) per year. An additional 81,500 km2 (31,500 miles2) of the western United States forested regions were exposed to fires due to increased aridity between 1984 and 2017.

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FlamMap 6.2: An introduction and overview of new capabilities

Webinar recording.

Description: This webinar will provide an introduction and overview of the FlamMap modeling system and its new capabilities with focus on several new additions:

  • Landscape Utility for the creation and extraction of LANDFIRE based landscape files
  • Spatial version of the First Order Fire Effects Model (FOFEM)
  • Additional support for raster formats
  • GeoTIFFs now supported when generating landscapes
  • Save Raster Outputs as Single GeoTIFF File
  • Measure Tool
  • New tools to edit and graph weather

Presenter: Chuck McHugh, Fire Spatial Analyst, USFS RMRS Missoula Fire Sciences Lab

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Warming weakens the night-time barrier to global fire

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This study shows that night-time fre intensity has increased, which is linked to hotter and drier nights. Our findings are based on global satellite observations of daytime and night-time fire detections and corresponding hourly climate data, from which we determine landcover-specific thresholds of VPD (VPDt), below which fire detections are very rare (less than 95 per cent modelled chance). Globally, daily minimum VPD increased by 25 per cent from 1979 to 2020. Across burnable lands, the annual number of flammable night-time hours—when VPD exceeds VPDt—increased by 110 hours, allowing five additional nights when flammability never ceases. Across nearly one-fifth of burnable lands, flammable nights increased by at least one week across this period. Globally, night fires have become 7.2 per cent more intense from 2003 to 2020, measured via a satellite record.

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