John T. Abatzoglou, Jennifer Balch, Bethany A. Bradley, Crystal A. Kolden
Year Published:

Cataloging Information

Fire Behavior
Fire & Fuels Modeling

NRFSN number: 17823
FRAMES RCS Number: 56070
Record updated: June 21, 2018

Large wildfires (>40 ha) account for the majority of burned area across the contiguous United States (US) and appropriate substantial suppression resources. A variety of environmental and social factors influence wildfire growth and whether a fire overcomes initial attack efforts and becomes a large wildfire. However, little is known about how these factors differ between lightning-caused and human-caused wildfires. This study examines differences in temperature, vapour pressure deficit, fuel moisture and wind speed for large and small lightning- and human-caused wildfires during the initial days of fire activity at ecoregion scales across the US. Large fires of both human and lightning origin occurred coincident with above-normal temperature and vapour pressure deficit and below-normal 100-hour dead fuel moisture compared with small fires. Large human-caused wildfires occurred, on average, coincident with higher wind speeds than small human-caused wildfires and large lightning-caused wildfires. These results suggest the importance of winds in driving rapid fire growth that can allow fires to overcome many of the factors that typically inhibit large human-caused fires. Additionally, such findings highlight the interplay between human activity and meteorological conditions and the importance of incorporating winds in modelling large-fire risk in human-dominated landscapes.


Abatzoglou, John T.; Balch, Jennifer K.; Bradley, Bethany A.; Kolden, Crystal A. 2018. Human-related ignitions concurrent with high winds promote large wildfires across the USA. International Journal of Wildland Fire 27(6):377-386.

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