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Fire Weather

The experimental fire potential index map uses satellite derived Relative Greenness, an NFDR fuel model map (both 1 km resolution), and an interpolated 10-hour timelag map as inputs to weight the relative influence of live and dead vegetation to fire potential. The scale ranges from 0 (low) to 100 (high). Except for 10-h moisture content, the calculations used in the National Fire Danger Rating System are not part of the Fire Potential Index.

The fire potential index is described by Burgan and others (1998). This paper was modified in 2000 to include more recent work. The revised paper is available online. The major modification consists of a new maximum live ratio map for the U.S. In the original formulation of the FPI algorithm, maximum live ratios were determined as a function of the live and dead loads assigned to each fuel model. However, this resulted in similar live ratios for fuel models that represent very different vegetation types--not a realistic situation. The effect was to overestimate the FPI in the eastern U.S. during summer, when the vegetation is normally very green. This dilemma was resolved by deriving a maximum live ratio map from the maximum NDVI map of the conterminous United States, under the assumption of a direct relationship between the two. A second modification was made to smooth the ten hour fuel moisture calculation near its upper and lower limits, thus avoiding calculation discontinuities.

If you have questions contact:

Bob Burgan, Retired Missoula Fire Sciences Lab PO Box 8089 Missoula, MT 59807 Ph: 406-728-0172 e-mail:
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