Spread Component (SC) (as used in the

National Fire Danger Rating System National Fire Danger Rating System (NFDRS) is used in the United States to provide a measure of the relative seriousness of burning conditions and threat of wildfires. Background John J. Keetch, a fire researcher in the southeast, wrote that "One ...

) is a rating of the forward rate of spread of a headfire.Deeming, et al., (1977) Deeming states that "the spread component is numerically equal to the theoretical ideal rate of spread expressed in feet-per-minute." This carefully worded statement indicates both

guideline A guideline is a statement by which to determine a course of action. A guideline aims to streamline particular processes according to a set routine or sound practice. Guidelines may be issued by and used by any organization (governmental or pri ...

s (theoretical) and cautions (ideal) that must be used when applying the spread component.

Wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

speed,

slope In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is used ...

, and fine fuel

moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

are key inputs in the calculations of the spread component, thus accounting for a high variability from day to day. The spread component is expressed on an open-ended scale; it has no upper limit.

References

External links

Inventory of the National Fire Danger Rating System Collection, 1911 - 2004
in the

Forest History Society The Forest History Society is an American non-profit organization dedicated to the preservation of forest and conservation history."Forest History Society." Echo Project. Center for History and New Media, George Mason University. http://echo.gmu. ...

Library and Archives, Durham, NC {{firefighting-stub Fire prevention Firefighting in the United States United States Forest Service Wildfire prevention