Time, in hours and fraction of hours, that a precipitation event lasts. More precisely, for fire danger rating purposes, the length of time that fuels are subjected to liquid water.

Those wildland areas where the combination of vegetation, topography, weather, and the threat of fire to life and property create difficult and dangerous problems.

Cargo, not attached to a parachute, that is dropped intentionally from an aircraft in flight.

That fraction of the soil that includes plant and animal residues at various stages of decomposition, cells and tissues of soil organisms, and substances synthesized by the soil population.

Period of time when suppression crews, equipment, and aircraft are kept ready for deployment on short notice; usually employed when fire danger reaches a predetermined severity index.

The leading edge of a relatively cold air mass which displaces warmer air, causing it to rise. If the lifted air contains enough moisture, cloudiness, precipitation and even thunderstorms may result. As fronts move through a region, in the Northern Hemisphere, the winds at a given location will experience a marked shift in direction. Ahead of an approaching cold front, winds will usually shift gradually from southeast to south, and on to southwest. As a cold front passes, winds shift rapidly to west, then northwest.

A helicopter flight condition in which the lifting rotor is driven entirely by action of air when the helicopter is in motion.

The ability of the wildland fire program to respond to current and anticipated workload needs for the area of concern.

An event measured by the occurrence of fire(s) that requires mobilization of additional resources from outside the fire event area.

A causative agent for wildland fire. For example, human or lightning.