The Lower Atmosphere Severity Index (often called the
Haines Index after retired RWU-4401 meteorologist Donald
Haines) describes the above-surface air mass as it affects large
and/or erratic wildland fires. LASI is most important when the
surface fire danger is high; if LASI is also high, it can lead to
The LASI should be considered along with a surface Fire
Danger Index for maximum effectiveness. Obviously, if surface
fuels are green and wet, that condition would be more important than
the state of the above-surface atmosphere.
The LASI is based on a two parameter model determined by the
environmental lapse rate of a layer of air, coupled with its moisture
content. The height of the layer of air depends on general
surface elevation above sea level. The layer selected varies
from region to region.
Time of computation of LASI is 0000 UTC. The results
are presented in a four-category adjective classification for
severity, from Very Low to High.
In 1998, the USDA Forest Service North Central Research
Station and the University of Wisconsin, Madison Department of
Atmospheric and Oceanic Sciences began making
forecasts of the Haines Index for fire weather available over the
world wide web. Through this cooperative agreement, 0-hour,
24-hour, and 48-hour forecasts of the Haines Index are available every
Since late 1998, these images have been archived and
analyzed. Using the 0-hour images, which reflect direct
observations of the atmosphere without any type of forecast, we have
created maps of the average Haines Index for each month available.
These maps can be used to note seasonal patterns in the Haines Index
and how conducive the atmosphere is to fostering large wildfires.
Publications can be obtained from your local library, the
appropriate journal, or the authors, if supplies remain.
- Regional analysis of Haines' LASI. Potter B. 1995.
Fire Management Notes. 55(3):30.
- The Haines index and Idaho wildfire growth. Werth
P, Ochoa R. 1990. Fire Management Notes. 51(4):9-13.
- A lower-atmosphere severity index for wildland fires.
Haines D. 1988. National Weather Digest. 13(2):23-27.
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