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Geographic Analysis and Monitoring Program
The convergence of large amounts of dry wildland fuels and weather favorable for fire ignition and spread signifies high potential for uncharacteristically large and dangerous fires. The ability to characterize the potential for hazardous fire activity requires measurements of fuel condition combined with information from weather forecasts. The availability of long fire histories adds a third dimension, fire probability, which can improve the ability to develop weekly forecasts of the location and number of large fires over a given region (Preisler and others, 2008).
The United States Geological Survey (USGS) uses moderate resolution satellite data to assess live fuel condition for estimating fire danger. Using 23 years of vegetation condition measurements, we are able to determine the relative greenness of current live fuels. High relative greenness values indicate the vegetation is healthy and vigorous; low greenness values indicate the vegetation is under stress, dry (possibly from drought), behind in annual development, or dead. Forest, shrub, and grassland vegetation with low relative greenness are susceptible to fire ignition during the fire season. The relative greenness for June 29, 2015, is shown in figure 1.
The fire potential index (FPI) integrates weather information from the National Digital Forecast Database (http://www.nws.noaa.gov/ndfd/) and satellite-derived vegetation condition information, and is used to identify the areas most susceptible to fire ignition (Burgan et.al., 1998). The combination of relative greenness and weather information provides an estimate of the moisture condition of the live and dead vegetation. The FPI provides local and regional fire planners with a quantitative measure of fire ignition risk. The FPI for June 29, 2015, is shown in figure 2.
Each day, the USGS, in collaboration with the U.S. Forest Service, produces 7-day forecasts for the FPI, the expected number of large fires per Predictive Service Area, and the probability for a fire to exceed 100 acres in size. On a weekly basis, assessments of the relative greenness, the Normalized Difference Vegetation Index (NDVI), and the departure from the average weekly NDVI (fig. 3) are also produced. All can be viewed or downloaded for local analysis from the following Web site (http://firedanger.cr.usgs.gov).
References
Preisler, H., Burgan, R., Eidenshink, J., and Klaver, J., 2008, Estimation and mapping of large wildfire probabilities based on satellite and gridded weather information: International Journal of Wildland Fire, v. 18, no. 5, p. 508–516.
Fire Science Web site: http://eros.usgs.gov/landscape-dynamics/fire-science
Fire Danger Monitoring and Forecasting Web site: http://firedanger.cr.usgs.gov/Burgan, R.E., Klaver, R.W., and Klaver, J.M., 1998, Fuel models and fire potential from satellite and surface observations: International Journal of Wildland Fire, v. 8, no. 3, p. 159–170.
National Weather Service, 2007, National Digital Forecast Database (NDFD): National Weather Service database, accessed August 21, 2012, at http://www.nws.noaa.gov/ndfd/.
For more specific fire danger project information
Stephen Howard (smhoward@usgs.gov)
Earth Resources Observation and Science (EROS) Center Mundt Federal Building Sioux Falls, South Dakota 57198
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