Glossary of Wildfire Terms

Palmer drought severity index (PDI): Technique for measuring impact of soil moisture changes on vegetation, for predicting fire danger and fire behavior.
Parallel attack: Fire containment method where crews construct a fireline at some distance from the edge of the fire (e.g., 100 yards) and then burn out the fuel in the buffer as the fireline is completed.
Perennial grasses: an extremely volatile fuel, after curing, in May, June, July, which can lead to large, fast fires that may reach larger fuels.
Point of origin: an element of fire behavior, indicating where a fire began, supporting further analysis of where the fire went or will go; evidence of specific origin is often obscured or destroyed by suppression tactics.
Prescribed burn: Deliberately ignited fire for the purpose of forest or prairie management, often to remove heavy fuel buildup or simulate natural cycles of fire in an ecosystem. Also called "controlled burn", even if it becomes uncontrollable.
Progressive hose lay: A method of deploying hoses along firelines during suppression and as they are built and reinforced, typically using 1½-inch supply lines, gated wyes and 1-inch lateral lines with nozzles (or at least spigot valves) every 100 feet or so. As the line progesses, more hoses and valves are added.
Project fire: Any large fire requiring extensive management and the establishment of a temporary infrastructure to support firefighting efforts, such as fire camps.
Pulaski: Combination axe and grub hoe tool with a straight handle, used for building handline. Also known as "P-tool"