The system that most federal and state land managers rely on to quantify wildfire danger in the United States was first developed in 1972. Updated in 1978 and 1988, the work is now complete on the third revision that began in 2000. Expected to be introduced two years ago, the latest edition is named “National Fire Danger Rating System 2016”.
The NFDRS tracks the effect of previous weather events through their effect on live and dead fuels and adjusts them accordingly based on future or predicted weather conditions. It is a numeric scaling of the potential over a large area for fires to ignite, spread, and require fire suppression action. It is derived by applying local observations of current or predicted conditions of fuel, weather, and topographic factors to a set of complex science-based equations.
“The [updated] system is being rolled out now”, Jon Wallace told us. Mr. Wallace is the Deputy Fire Management Coordinator for the Southeast Region of the U.S. Fish & Wildlife Service. He said, “An interagency group led by the USFS is hosting Fire Danger Operating Plan/NFDRS2016 workshops around the country to introduce the new system as well as to help people update or develop fire danger operating plans. The final replacement of the current system is scheduled for May of 2020. We wanted to have a pretty good transition period so that people would have time to compare the old system with the new system.”
Another approach for predicting wildfire danger
A group of meteorologists and others in Chile and the U.K. have developed what they describe as “a novel probabilistic wildfire prediction system”, a daily wildfire warning system designed to be used by land managers in Chile. It predicts one thing the NFDRS does not address, the severity of a fire that may occur (low, moderate, or high). It also specifically addresses probability of fire occurrence, for example, 25% to 50%. The product they settled on for communicating the forecast appears to be a little complex at first, with 16 “risk levels” which are grouped into four “risk colors”, green, yellow, amber, and red.