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BWCAW fire behavior model explanations

Model explanations

Owing to the July 4th 1999 BWCA blowdown event, NFDRS fuel model I (heavy slash) is being utilized to represent the changed conditions in the blowdown area. Significant decisions from Initial Attack Protocols to visitor use decisions such as fire restrictions, closures, etc., will be based on the fire behavior potential of the blowdown fuels.

The maps generated by the model apply the value taken at the Ely weather station to the entire blowdown (colored) area. This is because Ely is the only station in the area that consistently reports both observed and forecast values.

Short-term Fire Danger Index

For initial attack decisions, Burning Index (BI) will be utilized as it is tied directly to flame length and therefore is a good indicator of resistance to control.

Long-term Fire Danger Index

The Energy Release Component (ERC) will be used for preparedness level determinations and fire restrictions, and will be one of the criteria used for judging the need for closures and other restrictions.

Thresholds and Interpretations

ERC Range

BI
Range

Percentile

Blowdown
Index
Level

Interpretations

0 - 45

0 - 37

0

Low

Fires can be fought with ground forces using portable pumps. Aerial resources will be successful in catching fires.

Adjacent fuel types will act as fuelbreak.

Little or no fire activity outside blowdown. No resource shortages.

46 - 116

38 - 81

15th

Moderate

Fires can be fought with ground forces using portable pumps. Aerial resources will be successful in catching fires. Burnout with aerial ignition will be effective.

Adjacent fuel types will act as fuelbreak.

Fire activity outside blowdown will be minimal. No resource shortages expected.

117 - 174

82 - 115

40th

High

Ground forces not effective without aerial drops from heavy aircraft first. Burnout with aerial ignition should be effective.

Most adjacent fuel types will be effective in slowing fire spread and intensity.

Fire activity outside blowdown will begin to impact resource availability.

175 - 218

116 - 149

70th

Very High

Ground forces ineffective except for followup to air drops and mopup. Aerial drops from multiple aircraft are effective. Aerial burnout effective under low wind scenarios backed up by airdrops and pretreating.

After greenup, adjacent hardwood fuel types may still act as fuel breaks if little downed/dead fuels are present.

Fire activity outside fo blowdown will begin to cause minor impacts to available resources.

219+

150+

90th

Extreme

Ground forces should not be committed. Air drops will be ineffective on head of fire. Aerial burnout should not be used unless evening window presents itself.

All adjacent fuel types will carry fire, with crowning likely in conifer.

Fire activity outside of blowdown will likely cause resource shortages.