Haines Index climatology for the western United States

Abstract

In 1988, Donald Haines developed a Lower Atmospheric Severity Index (LASI), now called the Haines Index, for wildland fires based on the stability and moisture content of the lower atmosphere. In the high-elevation, western region of the United States, the index uses the 70-50 kPa lapse rate and the temperature-dew point spread at 70 kPa. The index varies between 2 and 6 with a category 6 indicating dry, unstable air, and category 2 moist, stable air. The potential for large fire growth and/or extreme fire behavior is very low when the index is 2, but high when the index is 6.Haines developed a rudimentary Haines Index climatology for his study using radiosonde data from Winslow, Arizona and Salem, Illinois for the year 1981. His priliminary results indicated 6 % of all fire season days should fall with the high-index category and 62 % in the very low-index category.This study establishes a more detailed, high-elevation Haines Index climatology for the western United States based on 1990-1995 upper air data from 20 radiosonde sited. Maps and frequency tables are constructed for June through October for the morning (1200 UTC) and afternoon (0000 UTC) upper air soundings.