That period of the fire season during which fires are expected to ignite most readily, to burn with greater than average intensity, and to create damages at an unacceptable level.

A woody perennial plant differing from a perennial herb by its persistent and woody stem; and from a tree by its low stature and habit of branching from the base.

Fine cracking of glass, usually from heat of fire.

The greatest 5-second average wind speed during the previous hour that exceeded 25 knots.

An aircraft of 12,500 pounds (5,669 kg) or less, maximum certificated takeoff weight.

The term for horizontal air currents merging together or approaching a single point, such as at the center of a low pressure area producing a net inflow of air. When this occurs in the lower atmosphere, the excess air is removed by rising air currents. Expansion of the rising air above a convergence zone results in cooling, which in turn often gives condensation (clouds) and sometimes precipitation. 

The expansion or spreading out of a horizontal wind field. Generally associated with high pressure and light winds.

Chemical powders that will, in very small quantities, tend to prevent other powders from caking and flocculating. Imparts free-flowing qualities to powder. Used with fire retardant chemicals.

A narrow finger or band of fuel that connects two or more patches or areas of wildland fuel.

The distance between the flame tip and the midpoint of the flame depth at the base of the flame (generally the ground surface), an indicator of fire intensity.