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Large Fire Potential and Fire Potential Indexes PDF

Large Fire Potential and Fire Potential Indexes

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USGS Interactive Large Fire Map Viewer

Fire Potential Index 7-day Forecast

Conditional Large Fire Probability

Expected Large Fires per PSA



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USGS EROS, in conjunction with the USFS PSW and Bob Burgan (USFS retired), has developed several new products for understanding and forecasting the probability of large wildland fires on all land in the conterminous U.S.


Existing products are utilized, specifically Relative Greenness (RG), the Fire Potential Index (FPI), and 7-day weather forecasts from the National Digital Forecast Database (NDFD) to produce 7-daily forecast maps of FPI, plus four large fire probability maps, and a table that presents the probability of large fires by Geographic Area Coordination Center (GACC) areas of responsibility. Example map product is shown in the figure to the right. All maps and GACC summary tables are updated daily.

  1. Fire Potential Index 7-day forecast: The FPI is most similar to the Energy Release Component of the National Fire Danger Rating System in that both are moisture related indexes and neither indicates the effect of wind on fire potential. The FPI indicates the estimated proportion (percentage) of the vegetation that is dry enough to burn, thus the FPI is highest when dead fuel moistures and vegetation greenness are low. The FPI is calculated once daily for the continental U.S. at a resolution of 1 square kilometer. Although these maps provide a relative measure of fuel flammability across the U.S., on a scale of 0 to 100, they do not indicate the chance that a large fire will occur. http://firedanger.cr.usgs.gov/firepotential.php
  2. Conditional Large Fire Probability: This map 'translates' the FPI map into a probability map. It shows how often we can expect a fire to burn more than 100 acres if a 1+ acre ignition occurred in a given km2 grid cell with vegetation flammability conditions similar to those indicated by the FPI map. http://firedanger.cr.usgs.gov/largefire.php
  3. Expected Number of Large Fires per PSA: This map takes into account both probability of ignition and conditional probability of spread (to 500+ acres in East and 1000+ acres in West*) given ignition. The map shows the total number of fires to expect in a given Predictive Service Area (PSA) and the degree of confidence for each expected value. http://firedanger.cr.usgs.gov/expectedpsa.php
Click to see enlarged image of the Large Fire Probability

The forecast fire potential index and large fire forecast products are described by Preisler,et al. in "Forecasting Distributions of Large Federal-lands Fires Utilizing Satellite and Gridded Weather Information."

Please contact Steven Howard, USGS EROS for further information.

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