The characteristics of a structure and its immediate surroundings within 100 feet; the SIZ may be extended (e.g., to 150 or 200 feet) in areas of steep terrain or dense, highly flammable vegetation. The SIZ is the key determinant for structure ignition potential during wildfire.

A communication aid designed to help firefighters develop an awareness of the local fire situation by providing a visual reference to fire danger rating.

The direction of fire spread identified as one of three categories: advancing, lateral, or backing.

Used to determine the aerobic capacity of fire suppression support personnel and assign physical fitness scores. The test consists of walking a specified distance, with or without a weighted pack, in a predetermined period of time, with altitude corrections. 

The prevalent or characteristic meteorological conditions of any place or region, and their extremes.

Analysis of one or more fire scars to determine individual tree fire frequency or mean fire intervals for specified areas.

Any of the processes that lead to upward vertical motion in the atmosphere. These processes may include low level convergence, heating or thermal convection, orographic lifting over the mountains, and frontal lifting.

A set of mathematical equations that can be used to predict certain aspects of fire behavior when provided with an assessment of fuel and environmental conditions.

The government furnishes all operating supplies after the equipment arrives at the incident.

Sudden increase in wind speed to at least 17 mph (15 knots) that is sustained for at least 1 minute but not more than 5 minutes.