# Spread Component

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'''Spread Component''' (SC) (as used in the [National Fire Danger Rating System](/source/NFDRS)) is a rating of the forward rate of spread of a [headfire](/source/wildfire).<ref>Deeming, et al., (1977)</ref> 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](/source/guideline)s (theoretical) and cautions (ideal) that must be used when applying the spread component. [Wind](/source/Wind) speed, [slope](/source/Grade_(slope)), and fine fuel [moisture](/source/moisture) 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==
{{Reflist}}

==External links==
* [http://www.foresthistory.org/ead/National_Fire_Danger_Rating_System.html Inventory of the National Fire Danger Rating System Collection, 1911 - 2004], in the [Forest History Society](/source/Forest_History_Society) Library and Archives, Durham, NC

{{firefighting-stub}}
Category:Fire prevention
Category:Firefighting in the United States
Category:United States Forest Service
Category:Wildfire prevention

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Adapted from the Wikipedia article [Spread Component](https://en.wikipedia.org/wiki/Spread_Component) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Spread_Component?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.