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 layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, needles, and leaves and immediately above the mineral soil.

The top layer of forest floor, composed of loose debris of dead sticks, branches, twigs, and recently fallen leaves or needles; little altered in structure by decomposition.

Layer of decomposed organic matter on the forest floor beneath the fermentation layer and directly above the soil. It is that part of the duff in which decomposition has rendered vegetation unrecognizable and mixing of soil and organic matter is underway.

Two or more firefighters stationed at a strategic location for initial action on fires. Duties are essentially the same as those of individual firefighters.