HAINES INDEX

        The Haines Index is a measure of atmospheric stability (or instability) and is represented numerically ranging from 2 through 6.  The higher the number the less stable the atmosphere.  What this means to a wildland firefighter is the less stable the atmosphere the greater the likelihood of extreme fire behavior such as blow-ups, burnovers, and spotting across the fireline to name a few.  The Haines Index gives us a measure of how likely these extreme behaviors are on any given day.  A 2 or 3 tells us they are relatively unlikely.  A 4 represents a moderate risk, extreme fire behavior is possible, while a 5 or 6 tells us to be on full alert because extreme fire behavior is not only possible but very likely.

        There are some field indicators of atmospheric instability as well.  Have you ever seen an empty potato chip bag carried into the sky by the wind or perhaps a whirlwind moving across a field picking up leaves and other small lightweight debris along its way?  These are just a couple of the indicators a wildland firefighter look at while enroute to and on a wildland fire.  These thing indicate the likelihood for extreme fire behavior and tell us to be extra cautious while on the fireline.