Assessment of New Hampshire red flag criteria

Red Flag Watches and Warnings advise wildland firefighters of expected fire weather that can cause “problem fire behavior”, which is generally defined as fire behavior that exhibits above average rates of spread, flame lengths, and resistance to control for a given fuel model in a particular area.

The National Weather Service is charged with issuing Red Flag Watches and Warnings when certain pre-determined fire weather parameters are forecast. These parameters are set annually in cooperation with wildland fire agencies, and have traditionally been set utilizing past experience as the primary selection tool. However, few methods exist to verify the applicability of these watches and warnings. Similarly, little work has been done to locally define the fire behavior the watches and warnings were intended to predict, or to verify the fire behavior of wildfires burning under the pre-set parameters.

This presentation discusses an assessment of Red Flag Criteria for the Manchester, New Hampshire area utilizing a combination of statistical analysis and fire behavior modeling and analysis tools. Specifically, the analysis objectives include: 1) corroborate historic Red Flag days with actual or modeled fire behavior; 2) identify “problem fire behavior” for a particular area utilizing fire analysis tools; and 3) make recommendations for more applicable criteria.