The highest value for relative humidity measured at the observation site during the preceding 24-hour period.

Any fireline constructed at a distance from the fire perimeter concurrently with or after a line already constructed on or near to the perimeter of the fire. Generally constructed as an insurance measure in case the fire escapes control by the primary line. 

Multiple fire pattern indicators in relatively close proximity to each other which exhibit a consistent vector.

The net amount of heat that would be given off if fuel burns when it is absolutely dry, noted as Btu per pound of fuel.

A time-sensitive alert from an NWCG Committee to the wildland fire community regarding procedural changes, equipment information and/or use updates, potential safety hazards, etc. Yellow hash-marked bordered stationary will be associated with this type of alert.

Elements of a safety system used by fire fighters to routinely assess their current situation with respect to wildland firefighting hazards.

Filling pump with water when pump is taking water not under a pressure head. Necessary for centrifugal pumps.

The heat required to raise a unit mass of a substance one degree kelvin. It is the heat capacity of a system per unit mass; i.e., the ratio of the heat absorbed (or released) to the corresponding temperature rise (or fall).

Computerized multi-resource model that simulates the effects that naturally caused prescribed fires have on the future production of natural resources such as timber, forage, wildlife, recreation, and water.

An internet-based information system, providing national views of weather and fire potential, including national fire danger and weather maps and satellite-derived greenness maps.